My MAC desktop is super slow. Tried clearing many files but slow to start especially. Wheel spins when trying to open things.

There are many causes for slowness. The best way to determine the cause is to download, install and run the free app EtreCheck. Be sure to enable full disk access. Save the report it generates and post it below under"Additional text". It provides an overview of your computer which someone here can review and evaluate.

I see several issues:

• First the computer has not been restarted in 13 days, please restart it.
• Next I see that some adware has been downloaded. Download the free version of malwarebytes and run it, you can get it from malwarebytes.com of the Mac App Store.
• Next, your computer is a base model 21.5" iMac which is limited by only 8GB of RAM however the main bottle neck is the 5400 RPM HD.

The ONLY thing that can be done to make this computer faster is to buy an external USB SSD, then use a cloning app such as SuperDuper! or Carbon Copy Cloner to clone the internal HD to the new SSD. Then boot from the SSD and set it as your startup drive. This will help transform performance after the above has been done. However, the computer is now almost 9 years old and you may want to consider replacing it with a new Mac and this time if you buy another 21.5" get it with 16GB (32 GB is better) of RAM and the largest SSD you can afford.