If you have forgotten your password, there is no way to retrieve it. To access Remix Mini again, user has to reset the device.
This will erase all data previously stored.
Remix OS Version: B2015102401
How to reset:
1. Restart Remix Mini
2. While it's booting, under the Remix logo, the text "Press F2 to recovery" will show up
3. Press F2
4. Choose "wipe data/factory reset"
5. Choose "Yes"
Note: "Press F2 to enter Recovery system" ONLY works on version B2015102401 and versions after 2.0.100.