What to do with a tank treated with medications?

I'd do plenty of water changes and run activated charcoal in the filter. Activated charcoal removes many medications.

Yes! Of course, the charcoal. Been soo long since i've run with that stuff! Thanks.

Edit: Would filter carbon get it done?

There are two ways I might treat this tank. For the meds, diluting them will make them pretty much gone and harmless. For any diseaes which the meds might not have killed, I would go for a bleach soak overnight and then rinse and leave dry for a couple days. Since you are not planning to use the tank in the near future, I would go the bleach and dry route as it is the one which will do both remove the meds and kill any disease. Keep in mind that meds will often only kill the item they are designed to kill, so it is possible that leaving it running, some unexpected item could live on until a host was added. Also very easy to soak clean. I don't keep empty tanks running for long.

I'm pretty sure filter carbon is activated charcoal.

I have charcoal and carbon running now.

Bleach soak rinse and dry sounds good, going to do that tomorrow!! Should I bleach everything? Like filter, media, and the heater?