Step 1: Context.
The phrase "slide soft away" is a poetic expression used to describe death or departure.
Step 2: Interpretation.
It conveys the idea of a calm, gentle, and peaceful transition without pain or noise.
Step 3: Conclusion.
Thus, "slide soft away" refers to leaving life quietly and serenely.
“One of these days you’re going to talk yourself into a load of trouble,” her father said aggressively. What do you learn about Sophie’s father from these lines? (Going Places)