There is no tool to remove buildings (WHOLE BUILDINGS) including castles, etc

In creative we just have to aim at the grid we want to delete and hit Ctrl+X.

Doing that will delete the item and will put it in your hand ready to paste so hit Esc to close.

IF

You play survival = you must enable creative tools to be able to use Ctrl+X

Use Medieval Master tools > Hit Alt+F10, check the creative tools box on top, close the MM menu and you can delete, tho turn it OFF when done cause this is the God mode.

For your Mod problem = I really don't understand so you will to share more clues, sorry.

thanks

actual what you download from workshop are called mods because you have to install them into the game.

Looks like it, I have notice some members using this word "Mod" for all items on the Workshop.

when you are spawning objects or buildings how do you move the building closer to you it seems you can only spawn far away and i actual can;t see the ground so i can't always know if its flat.

Ctrl + mouse wheel = to move closer

Q and E = to retate

O = to reset to planet Gravity and for free rotation and pasting

I usualy add 1 stone cube 2/3 into the soil before pasting a blueprint especially to have a Bounding Box so it is easier to paste.

And I like to use those keys when on free rotation :

Insert, Home, Page Up, Del, End and Page Down

X is to free fly (hover)