You can close your position in up to four chunks as it moves your way. For example: 50% at 20 pips, 30% at 40 pips, and let the rest run.
The psychological benefit is real: you bank something early, which removes the anxiety of watching a profit evaporate. So is the downside: close too early and your winners stay small, dragging your expectancy down.
On MT4, closing part of a position gives the rest a new ticket number. Onyx accounts for this and tracks it another way, but if you see anything odd in your history, tell us.
Partial closes are available on the Elite plan.