I will repeat again what I said before.

Start the mag lotion a week before you change anything.
Take your blood pressure twice a day or more during that week.

Then taper off the diuretic to every other day. Still use the mag lotion and still take your blood pressure.

The next week taper to every 2 days off the drug. See what happens then.

Use the mag lotion EVERY DAY in a good amount. However you want to do it... morning and night or whatever.

Unless you approach this carefully and record what happens, you
will not learn anything useful.

Eventually you may be able to get off the drug. But then if your pressures go up, you can ASK for change from your doctor.
If your pressures are not over 140/90, you may be able to go without any drug.

You may have to find another doctor. Keep that in mind.
There is a movement now to not overtreat hypertension...not to overmedicate it. Borderline people, may be able to go without drugs. The magnesium lotion and/or oral may allow many to do this.