Firefox: How to Remove Words from Dictionary

How to remove words that you accidentally added to the Firefox dictionary:

Open the Firefox menu.
Open the Help menu (question mark).
Click on Troubleshooting Information.
Under Application Basics, find Profile Folder and click Show Folder.
Locate the file called persdict.dat.
Right-click on the file and open it with a text editor. There might be an option to Edit with [name of text editor] in the right-click menu.
Find the misspelled word and delete it.
You can also add new words here, with each word on a new line.