Remove "Feaured Image" module via mu plugin

Hi.

I am using the same Theme on several sites (various child themes), so do not particularly wish to modify the 'functions.php' file itself, in order to remove the "Featured Image" mudule from a multi-site!

Can anyone help with a piece of code suitable; as an 'MU-plugin'; that would remove the 'Features Image' option? Or suggest another method??

Thanking you in advance!

Regards

john