Uninstall is from the Programs And Features Control Panel
For complete uninstall, you should clear the following directories too
Default settings, dialer queue cache:
NOTE: files in this folder are preserved through upgrades. the Config.crm file in this folder is the connection to CRM so it can be pushed out to users (from a working client), so that new users do not have to enter connection info.
Application, including log file:
To uninstall all entities from CRM, you use the Uninstall System on the Dynamics Telephony COG Menu.
NOTE: You will not see this item unless your CRM user has a Role called “Dynamics Telephony Uninstall” – the role does not need any special permissions.
ALSO, you need to have it allowed under Admin Only Access in the Dynamics Telephony settings