Settings > Media Management > File Management > Recycling Bin
The path appears after you browse and select one, but it doesn’t seem to save (even if you click Save at the top of the settings). Once you leave the settings and re-enter, the Recycling Bin path you entered is gone.
Worked okay in Microsoft Edge though, so it might just be a Chrome issue.
Using Sonarr Ver. 2.0.0.3645