I'll assume this is an eggdrop. Login to your shell and get the process number of your bot.. To do that type psux at the prompt. Note the pid number and type kill -9 and whatever the process number is.
If your bot never connects to irc check that your ip and host are correct in the eggdrop config. You may also try choosing another vhost as some
shell's vhosts are over used.
To troubleshoot connection problems use the -n command when starting your bot and read the connection attempts.