Samsung
Remove a Synced Account auf Samsung
Samsung collects every account you add - Google, Samsung account, email, social apps - in one place under Accounts and backup. Each entry controls what data gets synced in the background: contacts, calendar, photos, app logins.
Logging out of an app like Facebook or Instagram often only ends the session inside that app. The account itself stays registered on the phone, and background sync for contacts or calendar entries linked to it keeps running until you remove the account from the system list.
To remove an account completely, go to Tap on Settings ➔ Tap on Accounts and backup ➔ Tap on Manage accounts ➔ Choose an Account ➔ Tap on Remove account ➔ Tap on Remove account to confirm.
This deletes the account and its sync settings from the device only. Nothing happens to the account itself online, so you can sign back in anytime. If you only want to pause syncing without removing the account, turn off the individual sync toggles inside that account instead of deleting it.