I'm using git gpg signing. I want to disable it. I've set .gitconfig
[user]
name = NAME
email = EMAIL
signingkey = KEY
...
[commit]
gpgsign = false
My commits are still signing by default.
PS: I also disabled from Sourcetree Repository/ Repository Settings/Security
tab. Both Sourcetree and terminal forces to use gpg.
You can disable this by running git config commit.gpgsign false
This sets the configuration locally instead of globally.
Putting this setting in .gitconfig worked for me with what you had, without the [user] configuration:
[commit]
gpgsign = false