No drain plug. What kind of trash, goop, solid, leaves, sludge.
Regardless, there are companies that clean gas tanks while in the boat. It isn't cheap but is a lot safer than you doing it yourself.
Note that if your 'trash' is sludge or goopy gas, you will need to service a lot more parts than just the tank.
Now my safety warning: If you decide to drain the tank yourself and I don't recommend that; if you pull the sender and use a pump to drain the tank, makes sure you get a pump that is approved for gasoline. It has to say so on the package.
Also note that legally getting rid of contaminated gas is also fairly expensive.