Убрать скобки с list python

arr = [
    [['Adrey'], [25], ['engineer'], ['SDI'], ['toyota']],
    [['Sasha'], [20], ['student'], ['MVI'], ['mers']]
]

res = [[i[0] for i in elem] for elem in arr]

print(res)

Можно воспользоваться модулем itertools:

from itertools import chain

arr = [
    [['Adrey'], [25], ['engineer'], ['SDI'], ['toyota']],
    [['Sasha'], [20], ['student'], ['MVI'], ['mers']]
]
new_list = [list(chain(*l)) for l in arr]
print(new_list)

Вывод:

[
    ['Adrey', 25, 'engineer', 'SDI', 'toyota'], 
    ['Sasha', 20, 'student', 'MVI', 'mers']
]