how to Stop Running SAP Transport request or Cancel the importing Transport request

 1. Execute transaction code STMS_IMPORT. 

Select Goto > Import Monitor. 

Under Execution, select the transport and right-click. Choose on Delete entry to stop the running transport

or you can also kill the tp process that are running in the OS level. For UNIX/Linux, you can execute the command

In Windows, you can open the Task Manager, search for tp process and end the process.