Last promise not fullfilled on first call - promise

Question

Here is some code, in a cloud function, on Parse-Server using promises.
It is supposed to be called once and do a certain job of removing some contents layed out in a tree stucture.
The problem is that I have to call the same code twice to get the job fully done.
If someone can take a look and say what is wrong, that will be very helpful.
Here is what happens, when the code is called for the first time. All the work is done, except the last removal.
That means the code from the line:
console.log("We finally remove the unit.");
and after is not executed.
When the code is run the second time, the last part is properly executed.
I may have done something incorrect with the promises, but I can't see what.
Parse.Cloud.define
("removeTheThing", function(request, response) {
var thingQuery;
thingQuery = .....;
.....
thingQuery.find().then
(function(resUnit) {
var secondLevelQuery;
secondLevelQuery = .....;
.....
secondLevelQuery.find().then
(function(resSentence) {
var thirdLevelQuery;
thirdLevelQuery = .....;
.....
thirdLevelQuery.find().then
(function(resTranslat) {
var fourthLevelQuery;
fourthLevelQuery = .....;
.....
fourthLevelQuery.find().then
(function(resExplain) {
var destroyPromises = [];
for (i = 0; i < resExplain.length; i++) {
destroyPromises.push(resExplain[i].destroy({}));
}
return Parse.Promise.when(destroyPromises);
}).then
(function() {
var destroyPromises = [];
for (iT = 0; iT < resTranslat.length; iT++) {
destroyPromises.push(resTranslat[iT].destroy({}));
}
return Parse.Promise.when(destroyPromises);
}).then
(function() {
var destroyPromises = [];
const s3 = new aws.S3();
for (iS = 0; iS < resSentence.length; iS++) {
// Let us remove the voice recording:
destroyPromises.push(s3.deleteObject({
Bucket: "londonspeak",
Key: resSentence[iS].get("audio")
}).promise());
destroyPromises.push(resSentence[iS].destroy({}));
}
return Parse.Promise.when(destroyPromises);
}).then
(function() {
console.log("We finally remove the unit.");
//return resUnit[0].destroy({});
//return Parse.Promise.when(resUnit[0].destroy({}));//Promise()
var destroyPromise = [];
destroyPromise.push(resUnit[0].destroy({}));
return Parse.Promise.when(destroyPromise);
}).then(response.success);
});
});
});
});