Project won't cook with C++ classes

Hi,

Recently, I have decided to expand my BP project with some C++. I used the content browsers right-click menu to create a few C++ classes. Then, I imported a first-person characterCPP, and after a while I deleted it. Now, when I’m trying to cook the project, there are so many errors that I really don’t know what the problem could possibly be.
One of the errors is this:

UATHelper: Packaging (Windows
(64-bit)): LogWindows: Error:
[Callstack] 0x00007fff85bc3034
KERNEL32.DLL!UnknownFunction

Thanks for any help!

EDIT: after deleting the C++ assets, when I’m trying to open the project, it asks to rebuild something. If I say yes, it won’t finish and tells me to do it manually and when I say no, the project doesn’t open. How do I get rid of all C++ things the engine generated by creating the classes?

EDIT2: I found out that THE MAP (the level) contains the C++ thingies, not the project itself. Is there any way to get them out of the level asset?

Thanks