To remove the RTI cartridge from an application named myApp, from the command line:
$ rhc cartridge remove -c ocsystemsinc-rti -a myApp
Password: ***************

Removing a cartridge is a destructive operation that may result in loss of data associated with the cartridge.

Are you sure you wish to remove ocsystemsinc-rti-3.4.1 from 'myApp'? (yes|no): yes

Removing ocsystemsinc-rti-3.4.1 from 'myApp' ... removed  
To complete the removal process you need to restart your application.