Welcome H King Kong:
There is not a good way to de-lime the water heater. Whatever you put in there goes into your drinking water supply; they are conneceted.
You might try a drain-down and turn the water supply on intermittently to wash the scale out. Most of the scale is crusted up in there though and won't come out. The only fix is a new water heater, 10 years is the low-average life of it.
A whole house water filter might preserve the new one longer but you just have an extra high mineral content there and it will always be a problem.