Have been invested in NIKKO AM ETF for a year, should i withdraw their funds from it to reduce the losses?

Yes, no one has the answer.

psychology could dictate that we at least wait till break even, because we dislike realized losses. however STI investing anyway was no good idea over the last decade even calculating in the high dividends.

Buying only a big and cheap global passive stock indexing ETF (SWRD, VT) could be the brst answer when you want to switch to something different.

It depends on whether your alternative plan works. After you withdraw, where are you going to place it in? Surely, SG has not recovered to pre-covid level, but for US, it is at all time high level? Which one has a better risk-reward profile?

No one has the answer to it. dyodd