how do I remove a word from my Thunderbird dictionary?

[ToddAndMargo]

Hi All,

Fedora 32, x64

thunderbird-68.11.0-1.fc32.x86_64

I thought I'd ask this over here as there are
some really smart folks over here.

:-)

I want to remove "yo" from my dictionary.  It is
not in my custom dictionary, so how do I get rid
of it from my standard dictionary?

Many thanks,
-T