"Material is configurable" indicator in material master record

Hallo, SAP gurus!

I have a problem:

in my SAP system there is a material whose indicator "material is configurable" is set. Due to this I cannot hold calculations of this material on. How can I clear this indicator(it's grayed and I can't modify it)?

I experimented with BOMs for this material and tried to create several BOMs and I managed as I understand. Probably this could influence setting "material is configurable" flag. Because I could hold calculations on this material before.

Need help!

Thanks!