First, it is possible to delete the earlier partitions and then use GParted to resize a partition to occupy the earlier space. The problem with this is that it involves moving the start of the filesystem, and since filesystem data structures are defined relative to the beginning of the filesystem, the result of this operation is that a lot
of critical filesystem data must be recomputed and rewritten. This is both time-consuming and risky. I don't recommend doing it without a backup. It will succeed most of the time, but do you really want to take the chance that you'll be one of the minority of people for whom it fails?
One alternative is to create a new partition in the freed space and mount it within the existing directory tree, then move a subset of your data to that space. It looks like you're using auto-mounting in the /media directory tree, so to do this you'd need to switch to mounting the partitions via /etc/fstab. This might make things cleaner or more convenient, though, so it's not necessarily bad. Suppose for the sake of argument that you decide that you've got a bunch of MP3s that will fit in the new partition. You might do something like this:
- /home -- Your new /home on the SSD
- /home/jonass/data2 -- Your current /dev/sda6, currently mounted at /media/Data2
- /home/jonass/data2/mp3s or /home/jonass/mp3s -- The new partition you'll create in the free space
This approach is a bit inflexible, since it arbitrarily divides your free space between partitions, but it's a lot safer than trying to resize the start of a partition. If you've got a directory tree that's a bit smaller than the new free space and that you don't expect to grow significantly in size, this can be a good way to go.
In the long run, you might want to look into using a logical volume manager (LVM) setup. Using LVM, instead of putting filesystems in partitions, you put them in logical volumes, which are data structures within LVM partitions. The logical volumes can be managed a bit like files, which means that you can increase their size without touching their start points, even if the available space comes before the start of the logical volume. If you'd used LVMs for your current setup, you'd be able to easily increase the size of the logical volume to use the available space. Btrfs provides similar features without using an LVM, although it's officially experimental. If you wanted to begin moving in this direction, you could set up your freed space as an LVM or use Btrfs on it, and plan to convert more of your partitions in the future, whenever it becomes convenient. The main problem with LVMs is that Mint doesn't provide good install-time support for them.