What a mess!
Both parents are on rental lease.
Marriage is a wreck.
Is it possible to get one parent off the lease?
Can it be forced?

That would be up to the person or company holding the lease.

In most cases, I would say no.

It does not make sense to the business or landlord, to give up one of the people that they can collect from in the future if necessary.

I don't think you can force them, to remove anyone from the lease.

Generally no unless it is a rental and is going month by month you can inform your landlord that the second party will no longer be living there and they will have to confirm it with that person. But if it is a loan company holding a mortgage or something like they they don't generally remove anyone because as said that would hurt their chances of getting their money back.

Yes it is possible but normally there is a cost involved. Most lease agreements have a provision in them for penalties if the lease is broken early. That is one way to deal with it is to offer to pay the lease off by way of penalty and then re-lease the property in your name only. Of course your landlord will have to agree with it but at least you would be in legal compliance with most common law for rental lease unit housing.