#Resizing (Growing) the Partition
To grow your partition you can do it with the root mounted. To do this simply do:
sudo resize2fs /dev/sda1
Provided you already have the empty space ready to be merged. Afterward, I recommend rebooting for the changes to take effect correctly. The command above would resize to the maximum permitted. If you wish to resize to a particular size then simply add the size at the end:
sudo resize2fs /dev/sda1 25G