How to empty 1 cell of a cell variable which is part of a file?

I used matfile to create a 'writable' object consisting of variables in the file. I tried removing an element in one of the variables and I met with the error - "A null assignment can have only one non-colon index." How do I solve this issue? The code is as follows:

A = {};
B = cell(10,1);
save filework.mat A B -v7.3;
exampleobject = matfile('filework.mat', 'Writable', true);
for i = 1:10
  B{i} = 2*i;
  exampleobject.A(1,i) = B(i,1);
end
exampleobject.A(1,6) = [];

Answer 1

[per isakson]

"How to empty 1 cell of a cell variable" What exactly do you mean by empty? The syntax you use make me think you want to remove one cell to make A shorter.

Replacing

exampleobject.A(1,6) = [];

by

exampleobject.A(1,6) = {[]};

will change the value of one cell to empty.

K>> exampleobject.A
ans = 
    [2]    [4]    [6]    [8]    [10]    []    [14]    [16]    [18]    [20]

"A null assignment can have only one non-colon index." says that A(1,6) need to be replaced by A(:,6), but that seems not to work.

[Viswanath Hariharan]

I want to make A one cell shorter actually.

[per isakson]

In R2016a

>> cac = num2cell( [1:12] )
cac = 
    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]    [9]    [10]    [11]    [12]
>> cac(1,6)=[];
A null assignment can have only one non-colon index. 
>> cac(:,6)=[]
cac = 
    [1]    [2]    [3]    [4]    [5]    [7]    [8]    [9]    [10]    [11]    [12]
>> cssm
Error using cssm (line 10)
Cannot save an empty array in variable 'A'. 
>>

where line 10 of cssm is

exampleobject.A(:,6) = [];

[] is short-hand for "remove", but that doesn't seem to be implemented for mat-file-objects in R2016a. The error message indicates that Matlab tries an assignment.