That's kind of tricky to answer with the limited information available. You have the string "ABC" here in "ABC-Sharepoint", but you were interested in that part in the output. Are you looking for the first instance of "\ABC\" and then everything else in the string? Or everything after "C:\Development\Work\ABC-SharePoint\"? Something else entirely?
Here's one example that gives you everything after (and including) the first instance of a folder named exactly ABC (not case sensitive).
This particular example uses a regular expression, which is a very powerful technique that is also a pain in the butt to read. Another alternative would be to split the string on the backslashes (or use the Split-Path cmdlet) and loop over the resulting array yourself to find the first instance of "ABC", then join the rest of the array together. That code might look like this: