Scrutinizer provides a sophisticated system for filtering issues that do not make sense in your context, or are simply false-positives.
If you want to ignore a false-positive, simply click the Cross button in the top right of an issue:
If you would like to disable a certain type of check, the easiest way is to set-up an advanced filter. This works like ignoring false-positives, but applies to all issues of the same type. Doing so is very simple, first hover the Cross button in the top right of an issue:
On the opening modal dialog, you can widen the scope of the filter if you like. By default, we will only filter identical types of this issue, if you like we can also filter similar like the one found:
If you would like to view, or remove a filter, you can do so in your repository settings: