If BuddyPress @mentions are confusing your site users or you don’t need this feature of BuddyPress then you can easily disable mentions using BuddyPress No Mentions plugin in your WordPress site.
Install & activate BuddyPress No Mentions and that’s all but if you need to do more customization like by default BuddyPress No Mentions plugin uses inline CSS for hiding few elements and in case you like to remove these elements then:
For removing @mentions tab from activity directory, copy over /bp-default/activity/index.php in your site’s child theme and then remove hardcoded <li id="activity-mentions"> list item.
For removing @user (?) button from the your site member’s profile page then copy over /bp-default/members/single/member-header.php in your site’s child theme and then remove hardcoded<span> from <h2>.
And after this disable inline CSS by adding following code in your site wp-config.php which is present in your WordPress root directory:
define( BP_NO_MENTIONS_DISABLE_INLINE_CSS’, true );