Yes, you can mark a vulnerability as 'ignored' using the following procedure:
- View the vulnerability details
- Click on 'create ticket' or 'create workflow'
- When the ticket is created, modify it, and set it to 'Ignore'. We recommend you write in the notes why you are not going to fix it
This will open a ticket for this issue, and mark the ticket state as 'ignore', meaning it will not appear in the reports or in the statistics. You can still search for this vulnerability specifically (Vulnerabilities->Details will give you the option to search for 'ignored' vulnerabilities) and you can also go to the 'tickets' page and see it there.
Changing the ticket state from ignore to something else will show the vulnerability again.