Even when you delete them from the SEPM, they will re-populate with the next HB interval. You have to manually delete the slf files on the client using NoSLF tool or make it a unmanaged client.
or
the rough method thru SEPM
Install the extra clients as required and when SEP points out that there is a conflict, you delete the old ones, they may populate again but the licences will remain with the new ones.