How can I clean a matress from urine stains.?

Here's a method that should work well.

How to Clean Urine from a Mattress

If you catch the accident quickly, this section is for you. If the urine has already dried and created stains, skip down to the next section.

1. Strip the bed and put all your bedding in the washing machine as soon as possible.
2. Gather supplies.You will need white vinegar, baking soda, water, a spray bottle, a vacuum, and a few cleaning towels.
3. Using a cleaning towel or paper towels, gently blot the moist areas to soak up as much liquid as possible. Do not rub or scrub the mattress, as this risks pushing the urine further into the bed.
4. Create a solution of half water and half distilled vinegar, and put it in a spray bottle.
5. Spray the affected area with your vinegar solution.
6. Blot excess moisture out again using towels.
7. Cover the area with a generous layer of baking soda.
8. Let the baking soda sit on the mattress for as long as possible. We recommend at least 8 hours.
9. Vacuum off the baking soda and inspect the mattress, checking for signs of stains and urine odors.
10. If necessary, repeat steps 5 through 9 until the odor and stains are completely removed.

This process will generally remove the urine smell from a mattress and prevent permanent stains. Be sure to use plenty of baking soda and give it adequate time to soak up all of the excess moisture.

here are a couple of ideas Marli

https://casper.com/blog/how-to-get-pee-out-of-a-mattress/

https://www.yellowblissroad.com/clean-odors-stains-mattress/

Oh dear, here is what we did when out young granddaughters had accidents:

https://www.mattressfirm.com/blog/mattress-obsessed/how-to-clean-a-mattress-urine-stains/

Hello I have has success with spray Oxiclean type products.

Hi Marli, this is what we had to do when we looked after little ones that had an accident....and there are 2 solutions here

https://www.sleepfoundation.org/mattress-information/how-to-get-urine-smell-and-stains-out-of-a-mattress

In a spray bottle combine 8 ounces of hydrogen peroxide, 3 tablespoons of baking soda, and 2 to 4 drops of dish soap or liquid laundry detergent. Spray it on and let it dry. Vacuum - you may have to repeat the process.