>Is there any chance to remove IDENTITY of the column definition programaticly?
>I checked BOL but there is no such an option in ALTER TABLE.
>I tryed ALTER TABLE MyTable ALTER COLUMN ... Int w/o any success.

This not require a table copy:

ALTER TABLE MyTable ADD dummy INT
UPDATE MyTable SET dummy = idcolumn
ALTER TABLE MyTable DROP column idcolumn
EXEC sp_rename 'MyTable', 'idcolumn', 'COLUMN'