How to clear a git-svn repository password on MAC?

[YvesF]

The remote SVN repository URL and its password changed.

I changed the configuration file accordingly.

Trying to access the SVN repository using SourceTree ends up with the message:

git -c diff.mnemonicprefix=false -c core.quotepath=false -c credential.helper=sourcetree svn rebase Authentication realm: <https://svn.my_repository.com:1443> My_Repository_Name
Password for 'my_user_name': 
Authentication realm: <https://svn.my_repository.com:1443> My_Repository_Name
Username: error: git-svn died of signal 11
Completed with errors, see above

The configuration file is

[core]
repositoryformatversion = 0
filemode = true
bare = false
logallrefupdates = true
ignorecase = true
precomposeunicode = false
[svn-remote "svn"]
url = https://svn.my_repository.com/repos/repo_name/trunk
fetch = :refs/remotes/git-svn

I have SourceTree V2.0.2 on OSX 10.9.5

How can I force that SourceTree asks again for username and password?

Or is the problem something else?

Thanks so much for any hint.

Yves

[Seth]

Future reference, "Mac" is not an acronym, it is short for "Macintosh". Thus, should be "Mac", not "MAC". It is named after a type of apple (the fruit): http://en.wikipedia.org/wiki/McIntosh_(apple)