Acer TravelMate P245-MG - Manual (Page 35)

Changing to Windows 8.1 or Windows 7 - 35
Start Windows 8.1; from Start, type ‘recovery’ to open Acer Recovery
Management.
1. Select Restore Factory Settings.
2. Select Yes.
3. Select Windows 7, and then click OK and follow the instructions.
Windows will restart, replace Windows 8.1 with Windows 7, and then
start the Windows 7 setup process.
Changing BIOS settings
To change your BIOS settings, press <F2> when you see the Acer
logo during boot up.