1To lose something — to misplace it or no longer have it; also used for losing something one had, such as confidence or motivation.
駅で財布をなくしてしまって、本当に困った。
I lost my wallet at the station and was really in trouble.
大事な書類だから、なくさないように気をつけてね。
These are important documents, so be careful not to lose them.
何度も失敗して、すっかり自信をなくしてしまった。
After failing again and again, I completely lost my confidence.
切符をなくしたら、もう一度買い直さなければならない。
If you lose your ticket, you'll have to buy a new one.
2To get rid of, eliminate, remove, or abolish something undesirable. Often used for abstract things — eliminating discrimination, prejudice, waste, etc.
社会から差別をなくすことが私たちの目標だ。
Eliminating discrimination from society is our goal.
無駄な作業をなくして、業務を効率化した。
We eliminated wasteful tasks and made the work more efficient.
この制度は古いので、いっそなくしたほうがいいという声もある。
Some say this system is so outdated it would be better to abolish it altogether.