If they aren't what you are looking for that's ok - you just need to end it as quickly and painlessly as possible.
I suggest inviting them to a restaurant to which you tell them you will meet them there, then not show up, but every 15 minutes or so after the agreed meeting time sending them a text message saying 'sorry, i'll be there in 15 min'. After about 2 hours of this, send one saying, 'sorry, was hanging out with this really cool single girl I just met! Hope you enjoyed dinner!'
They'll get the message and be so angry with you they won't even start turning all inward and wondering what was wrong with them.