1. Check who is connected to the tty:
w
result:
08:50:26 up 152 days, 15:53, 2 users, load average: 0.00, 0.02, 0.01 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/0 wks1 08:27 0.00s 0.04s 0.00s w root pts/2 wks1 Mon09 15:41m 0.17s 0.17s -bash
2. Verify its PID
ps -u root |grep -i pts/2
3. kill the connection
kill -9 <PID>