If you have not already done so remove all documents etc from the partition you are deleting.
In easeuse select the partition you want to delete and click on the delete icon. this will look like the partition has being deleted but has not processed yet. click on the partition you want to resize and select resize/move. Just drag the side of the partition across to fill the bar. Click OK
Just below operations pending you should see the apply button.
If you have any files on the main partition I would suggest backing them up just in case something goes wrong.