A field set is created with a field attribute set to required and then added to a managed package. Upon installing this package, you cannot remove the required attribute as it is grey.
|Knowledge Article Number||000214845|
|Description||This behavior is considered working as designed.|
|Resolution||If you want to change the field set's field to not required, the package developer can set it to false in the packaging org and then upgrade the package, then the subscriber will be able to edit it after the new install(it will not be set to not required automatically but the ability to do so will open up).|