How to Approve Members to Your LinkedIn Group
To refuse membership, first select the check box next to each person you want to decline membership to the group, and then click the Decline button.
You can also click the Decline & Block button if you want to permanently block them from trying to join the group.
Similar to the approval process, you can decline people one at a time or all at once. (The easiest way to select everyone is to click the empty check box at the top of the list; the one with no name associated with it.) In either case (approval or decline), the user’s name disappears from the Request to Join page. Lastly, remember that you can remove someone from the group membership at any time after you initially approved him.