Unable to manipulate the object to a specific format in Javascript

I am trying to manipulate the object into my format of object but it’s not working.

I want to convert this array of objects:

let details =
[
 { tower_name: 'T1', flats: '["99", "96"]' },
 { tower_name: 'T2', flats: '["98"]' },
 { tower_name: 'T3', flats: '["505"]' }
]

And turn it into below format:

let towerFlatDetails = 
{
"T1": ["99", "96"],
"T2": ["98"],
"T3": ["505"],
}

I tried it this way, but it didn’t work:

let towerFlatDetails = {}
for (let i in details)
{
    towerFlatDetails.details[i].tower_name = JSON.parse(towerFlatDetails.details[i].flats)
}