Members of a group can be easily removed from the Xiaomi smartphone by simply tapping and holding the contact to remove it in the pop-up window that appears. The actual contacts are not deleted and remain in the contact list.

Android 10 (MIUI 12.0)
Step 1:  Open the  Contacts app
Step 2:  Tap on  My groups
Step 3:  Select a  group
Step 4:  Tap and hold a  contact
Step 5:  Tap on  Remove
  1. Open the Contacts app
  2. Tap on My groups
  3. Select a group
  4. Tap and hold a contact
  5. Tap on Remove

Xiaomi Instructions