Is it proper to take pleasure in the death of the wicked?

Answer:

"When it goes well with the righteous, the city rejoices, and when the wicked perish, there is joyful shouting" (Proverbs 11:10).

Everyone is happy when things go well with the righteous because the righteous is generous with his blessings (I Timothy 6:17-19). When the wicked die, it also brings happiness because the source of problems is removed. The focus here is on enjoying life and happiness, with justice triumphing over evil.

A similar observation from the opposite viewpoint is "When the righteous triumph, there is great glory, but when the wicked rise, men hide themselves" (Proverbs 28:12).

Perhaps you are thinking of: "Do not rejoice when your enemy falls, and do not let your heart be glad when he stumbles; or the LORD will see it and be displeased, and turn His anger away from him" (Proverbs 24:17-18). This almost seems contradictory, but notice that in Proverbs 11:10, it refers to a general feeling throughout the city, whereas in Proverbs 24:17-18, we are considering a personal enemy. We are not to seek vengeance on others (Romans 12:19-21). You can have an enemy, and he might not be a person totally given over to evil. Even with the wicked, we ought to desire their salvation. However, this doesn't mean we can't enjoy the lack of oppression, whether it comes from an evil person converting to God or an evil person no longer being able to commit evil.