If you have UltraEdit v12.20 or higher you can remove the shell integration for all files in the config dialog Configuration - File Associations
If you have a previous version you can run the UltraEdit setup and use the third option to remove the shell integration.
Or maybe more easily you copy following 5 green lines to a new ASCII text file, save it for example with name no_ue_context_menu.reg
and double click on this registry file to import it with Regedit into your registry which in this case deletes 2 registry keys. You need administrator privileges for this task.REGEDIT4
For more details about the shell integration of UltraEdit see right click to "open in UltraEdit"