There are two solutions if you want to get rid of the hidden reserved system partition that is not being TRIMmed:
ONE - Prevent it from being created on a fresh install
Not sure if it's what you are talking about, but it *is* possible to keep the hidden system reserved partition from being created on a clean install:
"If you don’t want this partition on your drive, the ideal thing to do is prevent it from being created in the first place. Rather than create a new partition in unallocated space from within the Windows installer, you can create a new partition consuming all the unallocated space with another disk-partitioning tool. Point the Windows installer at the partition you created and Windows will happily continue — it won’t attempt to resize your partition and create a System Reserved partition. The Windows installer will accept that there’s no room for System Reserved partition and install Windows onto a single partition. Bear in mind that you’re not saving an entire 100 MB or 350 MB by doing this, as the boot files will instead be installed on the main system partition."
and
"To stop the reserved space from being created from the gui you can:
Select create new partition (this will create reserve + install partition) Delete 2nd partition (leaving only the reserve) Highlight the reserved partition and then click expand (use the rest of the disk) Click next to complete installation
This is how we would do it at work because a) I hated that partition b) it would cause problems for imaging thousands of laptops/desktops depending on which imaging tool we would use."
Source:
What is the System Reserved Partition and Can You Delete It?
OR
TWO - Move the boot files from the reserved system partition to C: so you can then delete and merge the hidden partition back into C:
Using EasyBCD free to move the files:
Bootmgr - Move to C:\ with EasyBCD - Windows 7 Help Forums
Once it now boots from C: as it should after moving the system files, you can then use your fave partitioning tool to delete the reserved system partition and merge it into the full SSD partition.
I have done this both ways in the past with Windows 10 (should work for 8 and 7 too), and I hope this helps, as I am not 100% sure I understood your question =)
I end up with:
Note that my SSD is all one happy unit, no hidden partitions to worry about and I trim the whole thing manually once a week (as recommended by intel) with the intel SSD Toolbox, as it's an intel SSD. I just fresh installed again last night, thanks to installing shadow defender to 'try it out' and breaking my install =) LOL the irony, virtualizing software breaking my install because I wasn't running virtualizing software...
(In case you wonder the picture above displays 1 boot SSD, 2 HDDs and a USB Stick)