Is it safe to use CleanMyMac

Do not install any anti-virus or automated cleaning tools on your computer, and remove any that you have installed. They can use excessive computing resources and slow down your computer and possibly cause system damage. Recent macOS versions have security software as part of the operating system, do self-cleaning, and system software issues are best resolved using specific tools on a case by case basis. The same goes for malware removal. Being smart about what you download from where is the best protection against malware. Tools are always outdated. If you do get something try:

Malwarebytes - There are different versions available depending upon what features you want. For a single removal without ongoing monitoring you can probably use the free version.

If you think your Mac's performance is poor then run this analyzer and post the results here.

http://www.etresoft.com/etrecheck

EtreCheck on the Mac App Store - https://itunes.apple.com/app/etrecheck/id1423715984?mt=12

Using Etrecheck - https://discussions.apple.com/docs/DOC-6174

To save posting really long reports to the regular window, use the "paper" icon in the editor bar. See: https://discussions.apple.com/thread/250225837?answerId=250419632022#250419632022

I want to get a reliable program to Free Up GB's of space, ...

You do not need, nor should you use, any such program. They are very aggressively marketed scams that are as popular as they are destructive, and are just as prevalent for Windows PCs.

Unless macOS warns you by presenting an informative dialog that is running low on available storage space, the amount of unoccupied space is completely unrelated to a Mac's performance. If you should ever encounter that warning though, don't ignore it.

Please read How to free up storage space on your Mac - Apple Support and Optimize storage space on your Mac - Apple Support.

Installing and running any type of "cleaning" app may brick your Mac since some clean so well that they also delete needed system components. I would not allow anything of the kind anywhere within 10 miles of my Macs. You can easily move/delete files such as movies, videos, or photos yourself to an external hard drive; you can maintain a healthy amount of free space yourself and/or upgrade RAM or the hard drive (if the model allows it) and run Malwarebytes for Mac for free to get rid of malware/adware.

Piling on but it is important you get this:

1) the only cleaning software you need is built into the Mac operating system. If your hard drive is getting full it is your job to look for files you can delete or should consider moving to an external drive. I always recommend moving your iTunes library (music and video) to an external drive. That frees up lots of space

2) MalwareBytes free version is highly recommended. I don't recommend any other

3) a healthy stable Mac does require about 15-20GB free space but don't trust any program to clean for you. Cleaning software cleans your wallet but can leave your computer unstable and missing vital data.

You might also want to review this article:

https://discussions.apple.com/docs/DOC-8841