Step-by-Step Guide:
Open Telegram: Launch the Telegram app on your smartphone (Android or iOS).
Go to Settings:
On Android: Tap the three horizontal lines (☰) in the top-left corner to open the main menu, then tap "Settings".
On iOS: Tap the "Settings" (gear icon) in the bottom-right corner.
Navigate to Privacy and Security:
In the Settings menu, tap on "Privacy telegram number database and Security".
Find Data Settings / Contacts Section:
Scroll down until you find the "Contacts" section.
On Android: You'll usually see "Sync Contacts" and "Delete Synced Contacts" directly here.
On iOS: You might need to tap on "Data Settings" within "Privacy and Security" to find the "Contacts" section.
Toggle Off "Sync Contacts" (Highly Recommended First):
Locate the "Sync Contacts" toggle. Tap it to turn it OFF. This will prevent Telegram from adding new contacts from your phone or re-uploading old ones after you've deleted the existing synced data.
Tap "Delete Synced Contacts":
Immediately below or near the "Sync Contacts" toggle, you will see an option labeled "Delete Synced Contacts".
Tap on this option.
Confirm the Deletion.