How do I change the system to boot into text mode (runlevel 3) instead of the graphical login (runlevel 5)?

In order to change what runlevel the system boots to, modify the /etc/inittab file. This is a sample from the inittab file:

# Default runlevel. The runlevels used by RHS are:
#   0 – halt (Do NOT set initdefault to this)
#   1 – Single user mode
#   2 – Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 – Full multiuser mode
#   4 – unused
#   5 – X11
#   6 – reboot (Do NOT set initdefault to this)
runlevel is determined by this line:

Change the above line to:

and your system will now boot to runlevel 3 or text mode.