I have reduced my salt intake to almost zero for a couple of months after my blood pressure first shoot straight to 220/110mmHg but when I left my medication after two months in favor of low salt mostly vegetarian diet my systolic b.p. never came back to the normal level.
You can't just stop medications like that without consulting with your doctor. Some drugs can cause rebound hypertension on sudden withdrawl.
Tests I would advise - kidney function tests to look for renal disease.
Blood electrolytes(mainly Na+, K+)
Also urinary metanephrines or VMA to rule out phaeochromocytoma(rare).
Diet control reduces the BP, but at your level, you will need a multi pronged approach.
Low salt, low cholesterol diet. Moderate exercise like swimming, cycling, brisk walks or jogging for something like 40 min daily.
Continue medications, and get the dose adjusted by your treating physician according to the control level.
The diastolic should be maintained below 90 mm Hg.
Lose weight if you're at an unhealthy level(BMI is a good indicator) .
Lastly, sometimes the issue is genetic, and your main recourse is drugs.
Edit- get a cholesterol test and ECG, for a thorough workup.