Hmm. If his high BP was largely due to lifestyle ie being overweight, not enough exercise, poor diet, high salt intake, and he has rectified those things then it may not be such a problem. But it depends on how high it ws before he went on the meds - lifestyle can usually bring about around a 10mmHg reduction so if it was really high before then that alone wouldn't really do it.
Many BP meds can have side effects so if he was having problems with his particular med then he should have told them of s/e at his review so they could try something different (there are a fair few to choose from).
If he has uncontrolled high BP then he runs the risk of stroke, kidney failure, angina, aneurysms, eye problems, impotence and diabetes.
Before stopping his meds he should at least have his BP checked, preferably with a GP or practice nurse but if he won't go then with a home BP monitor (though they aren't all accurate).
I'm not sure I can help comment on the wisdom of his decision...but DH has recently come off his BP meds under medical supervision and will have a 24 hr monitor attached this week to check his BP is still under control. I would have serious concerns about him doing this without GP's knowledge
Can you suggest he cuts them out gradually rather than coming off them? Then he can judge whether he gets any high BP sypmtoms back (and may find the side effects go down enough to tolerate a little bit of medication). Or if he's on multiple types of medication, then just stop one at once to see the effect.
Please advise him to see his GP and discuss the need for continued treatment.
Losing a lot of weight and altering his lifestyle may have redcued his BP, but is unlikely to be a massive drop.
If he has stopped due to side effects, the GP may be able to stop or switch things around to help the situation.
The whole point of treating high BP is to reduce the risk of heart attacks and stroke, as well as organ damage. If he were to stop his treatment, his risk may increase again. He needs to speak to his GP, as they can go over this in more detail and use a risk stratification tool to help calculate and explain his risk better.