How to remove and not ignore maven modules

We have a project with four main parent modules, each having dozens to a hundred child modules, for example:

a, a-child1, a-child2, a-child1-child1

b, b-child1, b-child2, b-child3

Removing "a" from the project view removes it and automatically adds it to the ignored maven files. All its children are now shown on the root level of the project explorer. But I want to remove "a" and all its children. When I remove a module I then have to remove all its children, then their children and so on. No a lot of modules are enabled in the maven "Ignored files". But I don't want to ignore them, I want IntelliJ to completely forget about them.

I don't understand why the project view is kinda hierarchic when removing modules does not affetc child modules. The "Maven projects" view is next to useless when all four houndred maven modules are shown on the same level.

I cannot do any proper experiments with the stucture and maven modules because once imported I can't lose them without having to create a new project.

The only way I found to get actually rid of the maven modules was to manually remove them from several IntelliJ XML files in the project folder but that can't be the proper way.