With BP Private community Pro plugin allows you to restrict the user roles from sending friendship requests, from receiving friendship requests, from deleting the existing friend, and also set the maximum number of friends a user should have.
WB Plugins >> Community Pro>> Membership Restrictions, And select the user role from the dropdown.
Scroll down and open the tab Profile tabs Restrictions, and access the following settings
- Disable Sending Friendship Requests: Prevent users from sending friend requests.
- Disable Receiving Friendship Requests: Prevent users from receiving friendship requests.
- Delete Friends: Prevent users from deleting friends.
- Max Number Of Friends: Set how many friends this role can have?