Open Telegram
Tap the menu icon or go to Settings
Open Contacts
Find the contact you want to remove
Open the contact’s profile
Tap Edit or the three-dot menu
Select Delete Contact
Confirm the deletion
If the contact still appears, delete it from your phone’s contacts app
Sync Telegram contacts again if needed
On iPhone, go to Settings > Privacy and Security > Contacts and disable contact syncing if you want to stop future imports
On Android, go to Settings > Privacy and Security > Contacts and disable sync if needed