CMSIS library offers functionality such as delete mutex that RTX doesn't seem to offer. How is this achieved?, do I need to link to the library or I could implement that on my side?

My point is I'm actually developing an abstraction layer for a project and I came across that CMSIS library that I didn't know. I've already implemented what I need and had rejected using some functionality because that was not present on the Keil reference (RL-ARM User's Guide: Library Reference). Just after doing so, I realized of the existence of CMSIS and realized that there were functionality I find interesting such as deleting mutexes or semaphores that don't happen to be present on the keil reference. I don't understand why is that and would like to understand how does that work and possibly, move to code my abstraction layer on top of this library in case it is not too heavy. Has anyone had a similar experience and has any advice for me?.

Thanks for your help,

Nacho