Ok so I'm making some edits to an EA world and went to bulldoze a lot and realized the world file is populated, is it ok to just bulldoze the lot? Do they get deleted?
If not, how do I safely DE-POPULATE this world?

As far as I remember this will mess up the population. If you want to depopulate then you can clean the Global Layer. There is a tutorial (more or less) here: https://modthesims.info/showthread.php?t=473791

I assume you mean an occupied lot? Nothing bad will happen as long as you keep all families intact. You can move them to other lots (except deceased households, don't touch those, or they'll become unlinked from their tombstones, and fixing that is tricky), just make sure not to split them. Each EA world (except, I believe, Sunset Valley and Riverview) has an XML resource that specifies household members, and there shouldn't be any discrepancies between the data in that resource and the actual households.
Just in case you don't know about this, that XML needs to be imported back into the .world file after you finish editing, before exporting the world. If you want to completely depopulate the world, you can do that safely using the Total Annihilation option in NRaas MasterController. You also don't need to import the XML if you choose to delete EA's sims.
I wouldn't recommend cleaning the Global Layer just to depopulate a world. That layer can contain important objects, especially in EA's worlds. Deleting it in Isla Paradiso, for example, will break all houseboats. A safer method is to use NRaas MC instead.

That is true, thank you for pointing that out. There is also a big warning on the thread I linked about the downsides. But to safely de-populate a world this is the only method as it doesn't leave any leftovers behind. Also NRAAS MC does not work in CAW.

Ah, I forgot to mention that NRaas mods require using the makesim cheat to access their interactions in EIG. The created sim can be left as a townie or removed using Overwatch's Clean Up Homeless option.
NRaas mods are quite effective at deleting sims, Total Annihilation only leaves behind SNAP resources in the GlobalLayer file, which can be manually removed with S3PE (though it's not necessary, as the game won't reference them anymore). Aside from sims, most of the global layer consists of inventory objects, primarily books. Depending on the number of bookshelves, there could be hundreds or even thousands of books, but deleting them isn't necessary since the game automatically repopulates bookshelves when starting a new save.

All of the populated lots. The way I had done it is through edit in game, evicted each household and deleted from the clipboard before bulldozing the lot. After I wondered if this would cause issues. Currently there are 0 families, 0 sims at all, and 0 buildings.
Should I still do a total annihilation?

Since you've bulldozed everything, the method Norn linked above would probably be a better option in your case. If you don't want to do that, in theory, NRaas ErrorTrap should delete all leftover data, but I would delete sims properly myself just in case. Click on city hall (temporarily place one) > NRaas > MC > Sim > Advanced > Total Annihilation > Type of Sim (Or) > *cancel*, then if the list isn't empty, delete everyone in it.

Thanks for the tip! Will do.