Depends on which plataform you're currently playing:
You should go to C:\Users\[USERNAME]\AppData\Roaming\Macromedia\Flash Player\#SharedObjects\[BUNCH OF LETTERS and/or NUMBERS] on your computer and once there, go into the folder corresponding to where you've been playing:
-If it's from Fenoxo.com, it should be the com.fenoxo.##### or something similar.
-If it's from a local file (i.e. saved on your computer), it is located on the localhost folder.
-If it's from another place that you're playing (i.e. e621.net), it should have a folder named similarly to the domain (For example: e621.net's files are located in static1.e621.net).
EDIT: Forgot to say, the file name for those saves are CoC_#.sol (# is a number), so just delete the ones with the number that corresponds to the ones you want to get rid of.