You don’t have the option because you don’t have enough permissions on the project. You need Issue Administration permission.
See Project Permissions paragraph at https://docs.sonarqube.org/latest/instance-administration/security/ to understand permissions.
When you have Issue Administration permission on a project, you have pull down menus on issue Type (Code Smell, Bug, Severity), issue Severity (Blocker, Critical, Major, Minor, Info) and Issue status (Open, Confirmed, False Positive, Won’t Fix, Fixed) to perform manual changes, eg mark as False positive or Won’t Fix. The below screenshot shows the pulled down issue status menu
This Issue Administration permission should be used wisely and scarcely. If you abuse it by using it to artificially lower the importance of issues or even completely ignore them (eg “Won’t fix”) on a large scale, then you completely defeat the purpose of your code quality and security tool
In production, this is a permission probably only to be granted to senior developers/tech leads that should be the only one to perform those changes after some good thoughts.