Delegation is a loan that can be recalled at any time, for any reason, or never.

It is possible to transfer SP from one account to another so that ownership is fully completely subsumed, but the easiest way is probably to power down and then just transfer that STEEM wherever you want it.

I'm not sure that the idea of SP being a resource that can be loaned out is particularly awesome and creative; usury has been a part of human financial engagement for a thousand years in some parts of the world, and on Steemit it has led to the proliferation of bots which vote up less than quality content. Some of the side effects are less than desirable.

But it is a loan.