The browser automatically checks for and installs any updates.
Did you want to keep v77?

In the address bar, type about:crashes<enter>.
Note: If any reports do not have BP- in front of the numbers/letters, click it to submit them.

The crash report is several pages of data. We
need the report numbers to see the whole report.

Using your mouse, mark the most recent 7 - 10 Submitted crash reports, and copy them.
Now go to the reply box and paste them in.

For more help on crash reports, see;
https://support.mozilla.org/en-US/kb/firefox-crashes-asking-support

I would like to have the newest version. I am not seeing any crash reports. Firefox just freezes and I have to use task manager to stop it. Then when I open Firefox again, it gives me the Corrupted Profile popup. At this point 77.0 is installed.

If you want to reinstall Firefox, follow the instructions below.
If you just want to remove it, disregard the install instructions.

Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only>
Firefox itself: (Programs Folder)
And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

Download Firefox For All languages And Systems {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files
C:\Program Files (x86) Note: Check Both Folders

Mac: Open the "Applications" folder.
https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual.
If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop
++++++++++++++++++++++++++++
Look for, and remove any Mozilla or Firefox program folders.
Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner
if you have one. Then run the installer.
+++++++++++++++++++++++++++
If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode
This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia