How to cut out a part of your baseplate

So, I have this map idea and it was explained in an earlier post so here’s a link to that:
I changed my mind from the bridge and decided that I was going to go with the first island being shaped like this: and I know the shape is odd but I have a plan that there will be a forest at the wide area of the land and the area where the walls loop and the straightaway are going to be where the markets are. Now my question is, how do I cut out the portion of the baseplate that is outside of the walls? Would it be through solid modelling and if so, how?

I suggest just using the negate tool.

Using the regions tool, you can select large portions of the area and delete it.

just by moving/Reducing the size of the baseplate a little backwards or filling the spaces with a little sand from the Terrain editor that will make the green parts not visible .

So what I’d suggest is.
Get the part shape you want to make the shape cutout.
Go to model on the part shape and press negate. Overlap it with the baseplase. Hold CTRL and click on both parts on the explorer. Go back to model and press union.

I hope it helps ya.

you can either use negate tool or you can use Brick Knife plugin

adding the negate to something that is not very common would be a bad idea, since it would create a meaningless union using the negate would be used more for things like buildings, houses, etc.

Where can I find the regions tool? I checked all tabs and I couldn’t find it. Is it a plugin?

The regions tool is under the terrain menu.

You might want to try negating, or if that doesn’t work, you might need a plugin. If neither of those work, you could do it the hard way - just building it.

i would recommend unions, allthough they can be prone to corruptions (cursed unions).

just incase you dont know how to get rid of the base plate, its just like any other block, except its locked by default. all you need to do is unlock it, and you can interact with it like any other block.
you can also find it in eplorer even if it is locked.