Do we have the right to populate other planets?

[ultimategamer]

lets say hypothetically its in the future and the us people need to populate another planet. However, the only way to do this would be to drastically alter the planet's atmosphere, terrain, and stuff (which in the process would kill off any native life forms). Do we, as humans, have the right to do any, all, or none of the following:

1) Populate and alter another planet with no life at all
2) Populate and alter another planet with single celled organisms and the like
3) Populate and alter another planet with intelligent life.

I personally think that we should adhere to number 1, although 2 and 3 are possible as we've done similar things on earth (colonize islands and places like that, and in the process destroy much of what is there).

BTW: i took this topic from another forum and i wanted to post it here to see what your responses are