Remove command exclude specified file in Shell environment

The file structure under the root directory is listed below

+-root
     +-fileA.txt
     +-subdir1
   +-  a.txt
   +-
   b.txt +-c.txt +-subdir2 D.txt
   +-e.txt
   +-f.txt +-subdir3 +-subdir4 +-
     subdir5
     +-subdir6 +-subdir7
     +-subdir8
     +-subdir9
     ...

The aim is to remove all but the directory SubDir2 and file FileA.txt, and if one deletion is too inefficient, the shell command can be easily resolved

Ls|grep-v ' Subdir2\|filea.txt ' |xargs rm-r

The effect of the execution is as follows

+-root
     +-fileA.txt
     +-subdir2
          +-d.txt
          +-e.txt
          +-