This can also be done using the command:
/log off #channel - Details here:
https://en.wikichip.org/wiki/mirc/commands/logIf you were looking for a solution using a script, then try using code similar to this:
alias setlogs {
log on #channel
log off #myroom
log on #help
log off #test
}
Command to enter in the editbox:
/setlogs