you would need to delete the Solution pack files from the server manually, then delete the database from your MySQL Server.
Some of the files created by Power CMS Builder are shared by other WebAssist extensions, but the main files for power CMS to delete are in the admin_cms, WA_CMS, and WAGlobals folders.
for power store, should have uploaded the power store files to a subdirectory of your site, so you can delete the store directory to uninstall the solution.