To end your session with the remote system and keep FTP active on your local iSeries™, use the CLOSE FTP client subcommand:
CLose
The CLOSE subcommand allows you to remain in the FTP environment to open another FTP session on another system. Use the OPEN subcommand to establish a new connection with the same remote system or another remote system. Use the QUIT subcommand to end FTP service and return to the iSeries environment from which FTP was started.