ubuntu - Linux: increase sda1 partition size

I want to increase sda1 partition in my vm because its almost full.
I choosed dynamic size in virtualbox, but it doesn't seem to work (the size don't increase dynamicaly).
Here partitions state

Filesystem      Size  Used Avail Use% Mounted on
udev            610M     0  610M   0% /dev
tmpfs           126M  4,2M  122M   4% /run
/dev/sda1       6,6G  5,6G  619M  91% /
tmpfs           629M   92K  629M   1% /dev/shm
tmpfs           5,0M  4,0K  5,0M   1% /run/lock
tmpfs           629M     0  629M   0% /sys/fs/cgroup
tmpfs           126M   12K  126M   1% /run/user/1000

I resized partition size through windows with command line, i've got 15GB free, but when i tried to boot on a live cd of gparted, I can't resize sda1 because there is another partition between the sda1 partition and the greyed not used 15GB.

I tried command resize2f but it tells me that sda1 doesn't have the block I asked for.

Edit : result of command sudo parted -l

Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sda: 16,8GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:
Number  Start   End     Size    Type      File system     Flags
 1      1049kB  7232MB  7231MB  primary   ext4            boot
 2      7233MB  8589MB  1356MB  extended
 5      7233MB  8589MB  1356MB  logical   linux-swap(v1)

Is is possible to increase sda1 without deleting everything ? I already backed up my vm.
thanks