So you have an imported project bound to an SVN repo and after a while you want to change username/password you're using to access it. Seemingly there's no option for this in Eclipse. What I did was clearing the authentication data in TortoiseSVN. To do this select Settings in TortoiseSVN menu (eg. right-clicking on an SVN-controlled folder) and on the Saved data tab click on Clear button next to Authentication data. This will clear your saved passwords. Next time you commit or try to access the server, Eclipse will prompt you for your authentication data again.