Are you sure that the flash is the problem? Please try these first;

Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences<Enter> in the address bar

Select Advanced > General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Then restart.

https://support.mozilla.org/en-US/kb/troubleshoot-issues-with-plugins-fix-problems

https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues

As to removing the flash, what system are you running?

Much of the web is blank without Flash...

You can change the default permission of the Shockwave Flash plugin from "Always Activate" to "Ask to Activate". When you visit a site that wants to use Flash, an icon will appear in the address bar allowing you to activate Flash for the site. An "infobar" also may push down between the toolbar area and the page. If you don't see any good reason to allow Flash on the page, then just ignore it. This should avoid unnecessary/wasteful use of Flash and may be the right compromise for you.

Open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Then look for Shockwave Flash and adjust the permission level using the small button on the right.

What do you think?