Moored to a marina dock, removing trash aboard the boat is usually not a problem. Often there’s a trash can close to the dock, by the office or by the marina laundry. This is assuming you are in a marina that allows liveaboards.
Anchoring out takes more preparation. All discarded material must be in trash bags that are well tied up. The trash bag must be loaded on your dinghy to be disposed of ashore. Must make sure there are no tears or leak from the trash bag. If anyone sees you dumping anything whatsoever overboard from your dinghy or boat, it could escalate from complaint to police involvement
Getting into a trash removal routine helps quite a bit. Always have a supply of trash bags on hand and get more when running low on them. Going ashore every morning to a job, you can get a trash bag full and ready the night before. Leaving visual cues is a big help when removing trash aboard. How about always having a box of trash bags in plain sight by the companionway? If the trash bags are in the way you can’t miss them.
Keeping trash to a minimum is also something worth planning for. Getting food with minimal packaging helps, plus being able to fold or crumple it easily. Boxed items can be more troublesome, as boxes may have to be cut up and folded. Box edges could puncture trash bags just as you unload them and could make a mess. Canned food items take up more space and are heavier. Discarded can edges could also rip trash bags.
Removing trash will also help keep unwelcome bugs away. Letting food residue linger could bring on nasty smell inside a boat cabin. Anchoring in the hot summer when the cabin stays closed during the day, removing trash is essential.