Root is always there, you don't enable/disable, you just temporarily gain it's super-powers.
In general, root is the only user who can utterly obliterate a linux install. The ways to do this are plentiful and impossible to completely put down on a list. Just be careful. If you're following an instruction set, follow it faithfully.
And use root as little as possible. If you think a command might be hazardous, better to ask than reflash (or better yet, google - linux is extremely well documented on the internet)
In the end, using root is like being superman - you can do very cool/useful stuff, but you can also screw up enormously. There is no guideline other than experience
EDIT: try this for homework: find out what "rm -rf /" does and why it's a very bad idea to use it. This should show you the way to look up commands when unsure