How do you delete horizontal arrangement so fast?

how to delete horizontal arrangment so fast

Can you explain with more details what do you want to achieve?

I want to delete many things at once not one by one

As far as I know, you can't select multiple arrangements to delete. Anyway, you should take a look at some extension to create those elements dynamically:

[Free] CompCreator - create component dynamically - Extensions - MIT App Inventor Community