Erasing mail passwords contained in profiles completely

[Gezetthi]

Hi.
I want to confirm.
I have many past profiles(each about 100MB) of Thunderbird.
When I backup these folders,I'll erase

logins.json
key3.db
cert7.db
signons.sqlite

of all profiles.

After that,when got by somebody,
is retrievng passwords from those profiles impossible?
Is remains of passwords completely erased?

[DanRaisch]

What is your purpose in doing this? Are you trying to prevent others from using your email account to send and receive messages or are you trying to prevent others from reading the messages in those past profiles?

[Gezetthi]

I'm trying to prevent others from using my email account to send and receive messages.

[DanRaisch]

Then what you propose will work to prevent such use.

[Gezetthi]

Thank you!