You can run:
ps -ft pts/6 -t pts/9 -t pts/10
This would produce an output similar to:
UID PID PPID C STIME TTY TIME CMD
Vidya 772 2701 0 15:26 pts/6 00:00:00 bash
Vidya 773 2701 0 16:26 pts/9 00:00:00 bash
Vidya 774 2701 0 17:26 pts/10 00:00:00 bash
Grab the PID from the result.
Use the PIDs to kill the processes:
kill <PID1> <PID2> <PID3> ...
For the above example:
kill 772 773 774
If the process doesn’t gracefully terminate, just as a last option you can forcefully kill by sending a SIGKILL
kill -9 <PID>