and welcome.
Caution when delete partitions that you don't really know what is. It could be:
- Recovery partition also called "PQSERVICE" (specially on notebooks with pre-installed Windows)
- Linux Swap created after you installed Ubuntu
- Random data partition for documents
How do i check this information?
1.Press Master Key or Windows Key on keyboard
2.Search for Disk
and click on Disk app
3.On device menu, should be your hard disk on the list, click on it
4.On graphical display, will show details of your partitions and what describes them
Example of my HDD
- PQService (windows recovery pre-installed)
- System Reserved (essential files to Bios and boot)
- Acer Partition 3 (windows7)
- Extended Parititon (Linux,Linux Swap and document partition)
- Free unallocated space (needed information to create partitions, system reserved)
If it is free space or windows partition that you don't want its safe to remove and expand your Linux in-use partition

/dev/sda7
) – Avinash Raj May 09 '14 at 12:26