Don't think you can - however you can alter the subject line to say "Completed"
Cheers
Keith
Logged
Bateman - Ware, Herts, London. Partington - Liverpool - Devon - Manchester Foster - Liverpool - Manchester - Scotland Gates - Cumberland - Liverpool - Manchester - Australia Westwood - Ware, Herts
Generally we leave all posts on the boards even if they have been completed, just in case it helps another researcher. You never know a cousin you never knew about might read it and beat his/her way to your PC!