Carbon nanotubes (CNT) arrays are interesting because of the combination of their small size and outstanding physical properties. Vertically aligned carbon nanotubes (VACNTs), also named CNT forests or CNT turfs, show high heat conductivity and sufficient mechanical compliance to accommodate thermal expansion mismatch for use as advanced thermal interface materials. This paper reports measurements of the in-plane moduli of single-walled CNT (SWCNT) and multiwalled CNT (MWCNT) films. The mechanical response of these films is related to the nonhomogeneous morphology of the grown nanotubes, such as entangled nanotubes of a top crust layer where growth begins. Aligned nanotubes in the middle region, and lower density nanotubes in the bottom layer where growth terminates. To investigate how the entanglement layer governs the mechanical moduli of CNT films, we eliminate the effect of the crust layer by etching the CNT films from the top. A microfabricated cantilever technique shows that crust removal reduces the resulting moduli of the etched SWCNT films by as much as 40%, whereas the moduli of the etched MWCNT films does not change significantly, suggesting a minimal crust effect on the film modulus for thick films (>90 μm). This improved understanding will allows us to engineer the mechanical properties of CNT films for future applications.