Removing/Changing the Values on the y-axis

I’m creating a simple line chart and I was wondering if there is a way to remove the values on the y-axis (i.e., 0, 10, 20 …) and changing them to letters for example. I was also wondering if there’s a way to name the lines crossing-point so that this name is shown above it.

Thank you!

@KareemMesbah - Beside applying the only possible solution given by @mahfiaz, you can post an enhancement request at:
https://www.libreoffice.org/get-help/bug/?enhancement=yes
If you do so, please post the “bug nummer” here to enable others to comment. An enhancement request is logged under a “bug number”.

You could always draw white boxes over the graph to hide parts of it and write your own text.