Please follow up the steps below to remove the Appeon plug-ins for cross-browsers.
Step 1: End the AppeonMultiBrowserLauncher.exe process in the Task Manager.
Step 2: Clear off all the files under the directory C:\Users\%username%\AppData\Local\Appeon multi-browser plugin (which means to delete the folder AppeonMultiBrowser), for example, C:\Users\appeon (the username to log into the current machine)\AppData\Local\Appeon multi-browser plugin.