def flat(lis): flatList = [] # Iterate with outer list for element in lis: if type(element) is list: # Check if type is list than iterate through the sublist for item in element: flatList.append(item) else: flatList.append(element) return flatList lis = [[11, 22, 33, 44], [55, 66, 77], [88, 99, 100]] print('List', lis) print('Flat List', flat(lis))#removing elements from nested lists list[element].pop(nested_element)# If you know the index of the item you want, you can use the pop() method. It modifies the list and returns the removed item. L = ['a', ['bb', 'cc', 'dd'], 'e'] x = L[1].pop(1) print(L) # Prints ['a', ['bb', 'dd'], 'e'] # removed item print(x) # Prints ccList.appasf a sf sdf asd fas df asd f asd fasf