How?

Fill a spray bottle with a 50/50 solution of Dawn dish soap and vinegar. Spray it on the hard water stains and let it work. If they are tougher stains, you may have to scrub with a plastic scrubber!

I have always had good luck with CLR.

Ann's answer was the same I was going to give as well. A 50/50 solution of vinegar and dish soap will cling to the shower doors and help the vinegar get that scum off.

Mr Clean Magic Erasers no chemical just wet the sponge and use some elbow grease also I found Mighty Boss cleaner at Tractor Supply stores it is really good and once you get the soap scum off, use a squegee every time you shower to keep down the scum and hard water stains

Here are several ways from other Hometalkers

https://www.hometalk.com/search/posts?filter=clean%20shower%20doors

You’ll need an empty spray bottle, vinegar, and plain blue Dawn dish soap. Mix 1 cup of white vinegar with 3/4 cup of Dawn and microwave in a microwave safe glass container for 1 minute. Allow to cool and then, pour into a spray bottle.

To clean spray the solution on the shower door in an even mist, coating all the glass. Allow to sit on the surface for 15 minutes or so. When you come back to it, all you have to do is wipe the glass clean and then rinse well.

Yes!! Easiest way...https://www.exquisitelyunremarkable.com/2020/04/how-to-clean-glass-shower-doors.html

This will help: https://www.youtube.com/watch?v=XRDM1O2xmlk

This is what I use weekly and have not had water stains since using Heat up 1 cup of white vinegar, mix in about 1/4 cup of Dawn Premium. Not the dollar store kind, because it is too thin. When mixed, pour into a spray bottle and fill with water

I use Cider vinegar with equal part of water

This is an easy and useful formula: https://www.youtube.com/watch?v=XRDM1O2xmlk

This is another formula you can use: https://www.youtube.com/watch?v=XRDM1O2xmlk

You can also check out this blog post tutorial: https://www.pinterest.com/pin/11399805447619847/

Awesome cleaner from the Dollar store gets off most everything. Spray wipe and rinse well.

I use 50/50 vinegar and dish soap in a spray bottle. Spray on, let sit for a few, then scrubby off. Don't let it sit too long as vinegar dissolves and etches grout.

Mix equal part white vinegar and dish soap in a spray bottle. Then spray to your shower doors, and let the solution set for 20-30 minutes. Use cloth or scrub to wipe it out.

CLR .. that you can find at the hardware store

I use ,magic eraser from mr clean