Open the Contacts app
Tap the menu or More options
Select Merge duplicates or Fix and manage
Review the suggested duplicate contacts
Tap Merge all or Merge for each duplicate
If no merge option appears, open a duplicate contact
Tap Edit
Delete the extra contact details or tap Delete contact
Repeat for each duplicate contact
Open Google Contacts in a browser if needed
Sign in with the same Google account
Go to Merge and fix
Merge duplicate contacts from there
Sync contacts on your Android device after changes