Citrix Receiver Clen Up/Uninstall tool is very useful. This tool will assist to remove the Citrix Receiver completely from the Windows Machine.
Download Page: https://support.citrix.com/article/CTX137494
Note: Receiver cleanup utility is not required and not recommended while upgrading to the Receiver for Windows 4.4. Receiver for Windows 4.4 can upgrade from any older version of Receiver without the need of using the clean up utility.