When you post a job on Get on Board, it is very important that you manage the process within the platform and communicate with applicants throughout the selection process. If you do not close a process, you can continue to receive applicants and -by not giving feedback on their application- you affect the perception of professionals towards your company (people, in general, do not want to apply to companies that do not respond or do not update their processes).
However, if you have an old process that you forgot to close and you want to close it now, but you don't want to send messages with months of delay commenting on the discarded applicants, you can do so. Just uncheck the box "notify professional by email."