Just because you've mark something as deleted doesn't mean i'll delete it. There's a good chance im keeping it because I want it, or know others do, or am keeping it for archival purposes.
These should work on pretty much all platforms, pictures are from PC
Go to the Overseerr (Sign in with your Plex account) page for the item you want to request deleted, and select the following icon. This will be on the right hand side of the page on a PC, and toward the top of the page on mobile.

In the resulting pop-up window, select "Other" and leave a note stating you want the item deleted.

Affected Season appears to be broken, just put the season and episode in the description if applicable
You can also use this to report issues with the content, such as wrong episodes, potentially bad file, etc.