The Tab 2 A10-70 is based on a MediaTek chip, and it does not have secure boot enabled. That means it's very easy to flash firmwares and "roll back " to Android 5 or even 4.4 if you like.
To do this, you just need to know how to operate the MediaTek Smart Phone Flash Tool (SPFT), which is a freely available software for Windows and Linux. There are many guides for this tool on the web, though some of them contain dangerous misinformation (do not use the SPFT's "Format All" flash mode, or you'll lose important data).
Here's a brief how-to I made that tells you the most important things about the SPFT.
The SPFT can be downloaded here, and you'll also need this USB driver for Windows so that the SPFT can communicate with the tablet. A suitable scatter file for the Tab 2 A10-70 can be found here, or ususally in each firmware package. These SPFT firmware packages are usually 7-zip compressed (need to be extracted), and I've created and collected some on AndroidFileHost.
It's pretty much impossible to "brick" the tablet (save for an actual hardware fault), because a working firmware can always be restored via SPFT. Anyway, before you go and try to flash something with the SPFT, it's always a good idea to make a backup / "readback" of your current firmware. Particularly of the partitions that are unique to your device (proinfo and nvram). Also note that if you use the SPFT to make a readback of the preloader, you shouldn't flash that back to the device, because it'll have an incorrect format that needs to be fixed first. Readbacks of all other partitions can be flashed back without problem.