how can I save/remove custom sculpting brushes?

I guess is a stupid question but i really dont know how to do it and I didnt found any propper way.
I created a custom brush and i can work with it, no issues whatsoever, but each time I restart blender i loose my custom brush and i must create it again…
What i did was create an empty project, create my brush and save it as a startup file and now when i restart blender the brush is there, but just in that file, if I open another one I loose it again.

how could i save my brush so it will be always there with the deafault brushes in blender? And then, if want to remove it, how can i do it?, because i press the x button in the brush icon to remove it but when i restart blender is still there.

Thanks for the help!

You can’t. Brushes are only saved with the blend file. But can Ctrl u after importing the concerned one…

ah, ok, thanks for the answer.