نزع فتيل مخاوف الناس

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Note added at 6 mins (2020-03-09 15:07:06 GMT)
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أزال مخاوف/عوامل قلق الناس الخاصة بالأزمة المالية
https://context.reverso.net/translation/english-arabic/defus...

so as to avoid a word to word machine-like translation
I think this is the most accurate and meaning-kipping translation for this one.

This explanation is taken from معجم المعاني:

Translation and Meaning of defuse in Almaany English Arabic Dictionary
defused ( adjective ): broken

عاطِل ؛ مُعَطَّل

defuse ( verb ): make calm

خَفَّفَ ؛ قَتَلَ ؛ كَسَرَ حِدَّتَهُ

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Note added at 33 mins (2020-03-09 15:33:51 GMT)
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When the president visited the city in 1973, He defused the people's concerns about the financial crisis.
خفف الرئيس من مخاوف الناس حيال اﻷزمة المالية عندما زار المدينة عام 1973




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Note added at 35 mins (2020-03-09 15:36:17 GMT)
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Please pay attention to the suggested translations of other translators because SOME of them use Google Translate

To defuse something means to remove its fuse in order to disarm it and prevent it from causing harm. In this sense, the current context presents the concerns like a time bomb. They could reach a point of dire consequences of explosive proportions. The president acted to prevent or perhaps lessen the probability of such an outcome.

A literal translation of this metaphor has been provided by Rasha above, and I like it. It rings true and it does not read awkward. As a general rule, one should never reject a literal translation on sole the grounds that it is literal. one should reject it only if it is bad or if better ones are available. I dare to say that, a literal rendition deserves to be the first option to consider. It does not, however, have to be your final choice. The good news here is that other good options are available.

The second option is to aim for the meaning behind the meaning. The president did not eliminate the concerns, but he (or she) made them (relatively) innocuous. Of the answers provided above, at least two followed this approach. They are all pretty good.

When translating metaphors, there is, in addition to the literal approach and the interpretive approach, a third approach that you should also consider: replacing the metaphor with another that might be just as good or better in the target language. Let's see if we can apply this approach here.

The concerns were compared to a bomb in the source text. To what other things can concerns be compared? I can think of two things, but you could probably come up with others that are just as good.

Concerns can be like a weighty burden on people's minds. The weight can be crushing. Yassine's answer above is based on this approach:
خفف من مخاوف

In other words, the president made the weight of these concerns less crushing.

Concerns can also be like dark clouds that make the skies so gloomy and so pregnant with danger. With this image in mind, you can say something like:
قشع هموم الشعب بشأن الأزمة المالية

You have many options, none of which is bad. Trust your judgment and choose the one that provides the closest meaning and reads best in the target language.

Please note that I am not providing this merely as an answer to this specific question, but as a road map for future encounters with figurative expressions.