I have managed package that contains Product2 Custom Fields. Products are not supported in a group edition. So I want to remove those products fields from the Package. Is there any to remove those fields from the package?
It is possible to delete certain components from managed, released packages (including custom fields). Please refer to the documentation: Deleting Components in Managed Packages.
Be aware, that you have to open a case with the Salesforce support, in order to allow the deletion in the first place.
This question was asked earlier this year and a thorough answer is available here
The short answer is yes but only in a managed package in beta yet to be released.
IF you have released the beta managed package then you can delete the Custom Field but if you have released the managed version you wont be able to delete the Custom Field.
Its always good to release beta package and test in test orgs till the time development is complete. Only after one is sure a managed version should be released.