If you google this issue you will find that it has already been extensively discussed on this site.

If you are using Elgg 1.5 or above, there should be no problem deleting a user.

Hi, I did look at other posts and discussions and I found them to be confusing overall given the amount of them. That's why I wanted to be certain that it is ok to delete a user before I did so...and now I am :) Thanks

Is it okay if a message appears saying "sorry, we could not find the specified user" after deleting a member?

Yes - that shows that the delete worked.

Thanks a million Kevin. Good stuff!

So to be clear, there's no FIX to this, just have to take a loss and lose a member because they wanted to use a dot in their name? How about preventing dots from being used in the registration form in the first place...?

Just put a few lines of code in register.php top reject **any chars you want to block and throw an exception.

I have had good success changing the username in the database.

A rename does not mean dataloss for the user, unless he/she has uploaded photos with tidypics/files. In that case you could go to the Elgg data store directory and rename, but that's rather difficult.

Has anyone made the username field in register.php reject anything but a-z + 0-9? And if so, would you like to share it?

(Makes you wonder why this isn't standard in Elgg when it gives so much trouble)

Has anyone made the username field in register.php reject anything but a-z + 0-9? And if so, would you like to share it?

Yes, it was done, but not in register.php

\engine\lib\users.php, string 1156 in 1.6.1

$blacklist2 = '/\\"\'*& ?#%^(){}[]~?<>;|В¬`@-+=';

extend string with all unwanted chars in username (dot in your case)