had install a ubuntu dual boot with win xp to get a feel on how linux was like...

what if i just want ubuntu now and how should i go abt to remove win xp?

do i have to format and do a clean install?
or is there ways to just remove in win xp?

Welcome to LQ

Unless you need the disk space for now why not just keep win-xp?

hmm...
im using an old notebook with only 20gb of hdd size, might help a little i guess.

well, an easy thing to do to just KILL the windows is to boot only into ubuntu, then run "cfdisk" in a terminal.
use it (it's fairly simple, if you've never messed with partitions manually, I'm sure there are instructions on the internet!) to delete the partition containing windows. Then, maximize your Ubuntu partition. As maximization can be dangerous occasionally, I would recommend backing up any important data on the Ubuntu partition.

Also, back up EVERYTHING important on the WinXP partition, because It'll be gone. For good.

Does this help?

PS

I've never maximised a partition before. I think it should just use all new free space for the ubuntu. I don't think it'd eat ur swap or anything, so you might want to poke around and find out.

A safer, and probably easier way to do this would be just to do a fresh install of ubuntu.

You can use a program like gparted to remove Windows partition,but based on what you've said the best thing to do would be to reinstall Ubuntu again and use the entire hard disk during installation,that way Windows partition would be completly erased.You can set up separate partitions for / , /home and swap then easily.

20G HDD eh?
How much is windows using? Because I'd be tempted just to format the windows partition as ext3 (which will completely remove all windows files) and then mount that partition as /home.

That way, / and your 'buntu installation can stay as they are, you'll have free space on your / partition for new linux software, and a good-sized /home.