There's several solutions to this, both social and technical.
It's usually technically impossible to remove windows software after it's been run or installed. You can remove the superficial parts, but deeper modifications to the operating system will remain.
Please check the "social solutions" section of this answer for ways to prevent the software from being installed in the first place.
Make the software not able to run on your computer in a way that is provably the fault of the software vendor.
The simplest way to do this is to run a Linux live CD like Mint. Examity and ProctorU run only on Windows and Mac. You could also get a loaned a chromebook from someone, perhaps.
This makes no changes to your computer at all, and allows you to plausibly claim that the software doesn't work on your computer. If the school needs you to have a windows computer, they can provide one to you.
Clone your whole hard drive, aka fulldisk image, before the install.
This is possibly to do with free open-source tools like clonezilla. You'll need a second hard drive of at least the same size.
This is impossible to detect, and you can restore the image after the exam. This is technically hard, and might require a lot of reading, but should be 100% safe if done correctly.
Use a system modification detector to revert changes.
Software like Total Uninstaller can detect changes made to your system and revert them. You'll need to scan your computer before and after the installation of the malware.
Make a system restore point if no other option works, then restore it after you don't need the software anymore. This is the least safe option, as the software might delete or tamper the restore point.
Do a factory reset. This will erase all the data in the computer, so you'll have to backup everything to do that. This should be relatively safe, although it won't protect against the nastiest varieties of software, depending on your computer.
Social solutions are the safest option, since it prevents any infection from happening in the first place. They will also have the most long-lasting effects, since you're helping everyone around you.
It might be hard to achieve a social solution. This depends on your colleagues' values and attitude, your social circle and how comfortable you are reaching out to strangers for help.
Raise awareness of the problems and organize together with other students
Having this software is not in any students interest, so you simply shouldn't install it. To prevent repercussion, you'll need to do this as a group.
Your teacher won't fail the whole class. And if they try, you raise the issue to the school board. And if the school board doesn't do anything, you raise the problem to the school supervisory authority.
Ask for help and educate others around you.
You're not alone in this. See this article for example. You can try to reach out to people that are researching the problems, they'll probably have better guidance for you than superuser.
A local computer expert group would understand the problem and could potentially help explain the issues to your teachers and school.
Research the problem and find a solution
You can search for articles like this one, that show how this software exposes your name, address and passwords to hackers. Or this one about how students are watched live on camera remotely by people from random countries and can't move away even in extremely embarrassing situations.
Compile a list of the problems, and explain it to people around you. Try to understand what other students (and perhaps their families) care about the most. Talk with your teachers. Then research some more.
It's important that you don't just focus on the problem, but actually provide a solution that is better for everyone, students, teachers and schools.
Software like this does not prevent cheating. Students have managed to successfully cheat for centuries, even under close surveillance from their teachers and huge penalties.
The only way to reliably prevent cheating is to design the tests in a way that having access to material (including books, notes and the internet) is not sufficient to pass without having learned the material. That is your teachers responsibility. It is also the only way to check that you actually learned anything, instead of just memorizing.
If your teachers are concerned about students copying from each other, this can be reliably detected manually if the answers are long-form, or statistically if they're multiple choice. It's some extra work for teachers, for sure, but tests can be changed and that is their job.