dispose global object array to reuse object

dispose global object array to reuse object

I have a global object array in my form. I wanna change the array length
in several times. so I need to dispose it and new it with different
length.
as below code from Do you need to dispose of objects and set them to null?
((IDisposable)obj).Dispose();
I have error:
Error 1 Cannot convert type 'business.person.clssHeadCustomer[]' to
'System.IDisposable'
D:\acc2012\acc2012\WindowsFormsApplication1\hesabdari\frmCustomer.cs 80 14
presentation
now what should I do?!