Can't add TextMesh to gameObject

I cant add TextMesh to a cube because it conflicts with the existing MeshFilter, but I have previously destroyed such MeshFilter.

MeshFilter lettersMeshFilter = letterCube.GetComponent<MeshFilter>();
Destroy(lettersMeshFilter);

TextMesh textMesh = letterCube.AddComponent<TextMesh>() as TextMesh;

letterCube is created with no errors and I can set other attributes to it. letterCube is a gameObject, a Cube. Both letterCube and textMesh are created entirely on a script at runtime.

Any ideas?

Thanks in advanced!

Fixed it by changing:

Destroy(lettersMeshFilter);

For:

DestroyImmediate(lettersMeshFilter);