Excel has a TRIM function for removing leading and trailing spaces from a text string. I do not know of any function for removing spaces between characters. Now that I have said that I am sure someone will prove I am wrong.
If your column A entries are not constantly changing it might be simpler to use "Replace" in Excel's Edit menu. Just select the entire column and replace all instances of a space with nothing.
EDIT: If the one time use of Edit->Replace is not practical, the SUBSTITUTE function may work for you as described on this page from the MS site:
Remove spaces and nonprinting characters from text
http://office.microsoft.com/en-us/ex...561311033.aspx