Delete sender removes that LinkedIn sender from the workspace and frees the seat. Confirm in the dialog, because you cannot send from a deleted sender.
Delete and free the seat
Only Owner or admin can delete. The row menu is the path. Deleting is not a pause and not travel mode.
Sign in as Owner or admin.
Open Senders.
Open the row menu on the sender you no longer need.
Select Delete sender.
Confirm Delete sender in the dialog that names that sender.
The seat is free for another LinkedIn account after the delete finishes. Campaigns that used only that sender need a different sender before they can send. Unibox threads from that sender stay as history. They will not send again from the deleted row.
Before you delete
If you are at seat capacity, delete a sender you do not need, or choose a plan with more seats on Billing. Do not delete a sender to finish a verification code. Stay on the original row. If you only need a temporary halt, use travel mode or the kill switch instead.