My name is David.
You can use the Spotlight search app to find the location of your Downloads folder. To do this, click the magnifying glass icon in the upper-right corner of the menu bar, or press Command-Space. When Spotlight appears, type Downloads into Spotlight and press Enter and it should find the Downloads folder.
To uninstall Malwarebytes do the following:
On the menu bar, click Help.
Click Uninstall Malwarebytes.
Please let me know the result and if you need further assistance.
I can also assist you by directly connecting to your computer to perform both operations above if you prefer.
Also, please provide a positive rating (3, 4, or 5 star) as that is how I receive credit for my work.