The days that a user has access to equipment is controlled in their user settings, or via the access group settings if you are assigning equipment access to your users using access groups.

In the user/access group settings, select the Schedule tab and ensure that the schedule meets your requirements. For example, setting Saturday and Sunday to Never.

If a user has created a booking on the weekend and you thought you had removed weekend access for this user, double check where they have been assigned access to this equipment, as you may have updated the access group schedule but they might have been assigned access via a different group or in their individual settings, which might still have the default schedule set.