Board Thread:The Quarters - Q & A/@comment-90.223.205.134-20141021082635/@comment-24150802-20141021100328

I've already answered this question for you in the Tavern:

"@Grizel : When you leave a party, it does keep on existing, even with no one in it, but you certainly can re-use the name for any future party. :) The name you give a party isn't used to uniquely identify it, so it can be used again and again. You could also try to contact the user and ask them if they want to leave the party they are currently in. They might not have realised that they had to do that before you would be able to invite them."