Either you deregister from Switzerland, hand back your permit and cancel your health insurance but then you’ll have to apply for a new permit when you want to come back.
Or
You stay registered in Switzerland but then you have to continue to pay health insurance so choose the cheapest one possible with highest franchise for next year.
With a B permit you can be outside of Switzerland for up to six months without losing your permit. A C permit can be put in hold for a prolonged absence and that absolves you from having to pay the health insurance premiums but I don’t think that option exists for a B permit. (Or maybe it does but only for very good reasons).
As long as you want to keep your B-permit, you also need to be registered in Switzerland. If you are leaving for only 5 months, presumably that means you intend to return and therefore you will maintain a fixed base in Switzerland, including an address. All persons registered in Switzerland must, by law (with very few exceptions such as those with an even better international insurance from elsewhere) have an address and health insurance.
If you give up your connection to Switzerland, you're free to and indeed must cancel your health insurance. But thereby you'd also be giving up your permit.
The good news is that your Swiss health insurance should cover you for medical emergencies while abroad. Check this with them before you leave.
Where are you going for 5 months and what is the reason for the trip? These factors might have some bearing on reciprocal agreements with Switzerland or entitlement to treatment in case you need medical attention while abroad,