What you are actually revoking
When a third-party web service lets people sign in with LINE, two separate things exist: the service’s permission to use your LINE account, and whatever session that service has already opened in a browser or app. Ending the first does not automatically end the second.
This matters when you are worried that someone else is using a connection you no longer want. The useful question is not “how do I clean everything at once” but “which layer am I trying to close, and where is its control?”
| Layer | What it controls | Where the action happens |
|---|---|---|
| LINE password and two-factor authentication | Who can sign in to your LINE account | LINE account settings |
| Service authorization | Whether the web service may keep using your LINE login | LINE’s list of authorized or connected services |
| The service’s own session | Whether a browser on that service is still logged in | That service’s own account or session settings |
| Official-account chat | A message thread inside LINE | LINE chat, reviewed as a clue only |
Treat the rows as separate jobs. A change in one row is not evidence that another row has been handled.
The steps LINE’s guidance supports
For unauthorized access to a web service, LINE’s own guidance lists a specific sequence: change the LINE password, turn on two-factor authentication, and deauthorize the affected service.
LINE’s guidance for unauthorized web-service access includes changing the LINE password, enabling two-factor authentication, and deauthorizing the affected service. Source
A reader checklist built from that guidance, in order:
- Change the LINE password from within LINE’s account settings.
- Enable two-factor authentication if it is not already on.
- Find the affected service in LINE’s authorization or connected-services area and remove it.
- Open the external service itself, review its active sessions or devices if it offers such a view, and log out there.
- Keep a working recovery method for your own LINE account until you have finished checking everything.
Step 4 is the one people skip. It is also the reason a password change can feel like it “didn’t work.”
Why the external logout is a separate job
Closing the LINE side of the connection leaves the other side open. LINE’s guidance is explicit that a session already established on the external service is not necessarily ended by the LINE-side changes.
Changing the LINE password or deauthorizing a web service does not necessarily end a session already established on that external service; its logout must be handled separately. Source
The practical consequence: after deauthorizing, go to the service’s own settings and look for its session, device or “log out everywhere” controls. If the service does not publish such a control, that is a limitation of the service, not something LINE can close on its behalf. Do not assume the connection is dead just because the authorization entry is gone.
Where the controls are, and where this guide stops
The reviewed claims establish what LINE’s guidance covers, not the exact label or position of every menu in the current app or website. Menu names and layouts change between app versions, regions and account types. This guide therefore does not name a specific settings path it cannot verify.
What you can reasonably do:
- Look for account-security settings inside LINE itself for password and two-factor authentication.
- Look for an authorization, connected-apps or login-services area for the third-party service.
- Look for session or device management inside the external service.
- If a menu is not where you expect, check LINE’s current official help pages rather than following an old screenshot.
What this guide does not claim: that a single control closes every layer, that removal is instant everywhere, or that any particular order produces a guaranteed outcome. The sequence above follows the reviewed guidance; it is a proposed checklist, not a test we ran.
Reading a message from the service as a clue
A chat message from an official account or a service notification inside LINE is a lead, not proof. It can tell you that something happened, but it does not by itself establish who did it, from which device, or whether the account is still connected.
A safer reading:
- Note the date and what the message says.
- Check the authorization list for the named service.
- Check the service’s own session list.
- Change the password and enable two-factor authentication if you have not already.
Do not reply to the message with credentials, and do not treat an official-looking name or avatar as verification of the sender.
When the concern is broader than one service
If you are worried about what else is tied to your number or account rather than one specific connection, the next useful task is mapping the footprint before deciding what to close. See how to find all accounts linked to a phone number for that separate review, and keep the recovery method for each account you touch until you have finished.
What TraceSeek can and cannot do here
TraceSeek is a separate public-username lookup app. It searches publicly accessible profile candidates for a supplied username across 3,000+ platforms. It cannot change LINE settings, revoke a service authorization, log out of an external session, recover a private account or verify anyone’s identity. A public match is a lead, not proof of ownership.
If your reason for reviewing connections is to understand your own public footprint, that is the task TraceSeek addresses. It is not a cleanup tool for account security settings, and running a username search does not close any session.