What does surrender mean in Spirituality?
There is a lot we have that is not needed. The basic principle is that our troubles arise not from our deficiencies, but from our excesses. The problem in the inner sense (in the mental sense), is not that we lack in anything, our problem is that we have accumulated much that is useless, needless and just a burden. This is the point that we start from.
So if we start from this point, the process of spiritual activity is unburdening. The process involves letting go (dropping). In the way of knowledge or realization this unburdening happens because you see that the stuff that you have is unnecessary and toxic.
You come to look at your mind and see that your thoughts, emotions, fantasies, ideology, knowledge, self concepts are keeping you heavy, keeping you dull and lifeless, so you just drop them. Then, it is just called as renunciation.
Fundamentally, what is renunciation? Getting rid of something. This process of getting rid is given the name renunciation, if you apply the negative process of knowledge or realization. Negative in the sense it discounts, it looks at stuff and says — not right, not good, drop it. In the path of devotion, it is not yourself you really look at. It is a faint memory of the beloved that impels you.