Thanks for the answers!
I improved upon your code to work as intended so it perfectly fit my needs now:
@echo off
for /d %%a in (*) do (
cd "%%a"
for %%b in (*) do (
echo moving "%%a\%%b" to "%%a%%~xb"
move "%%b" "..\%%a%%~xb"
)
cd ..
rd "%%a"
)