Installing AROMA File Manager I have to break the pattern on someone's Android phone. I researched on Google and found a way of doing it with AROMA File Manager.

Do I have to install CWM or TWRP or can I use a custom recovery mode to extract AROMA File Manager's file? Does the phone need to be rooted or can it be done without root?
Yes,you need a custom recovery. Aroma runs within a custom recovery.
A custom recovery such as cwm or twrp can be installed without root on most phones, but you will most likely have to unlock the bootloader first.
Exact steps are dependant on what phone model you have.
Most phones are well covered on xda developers, google it.