Pretty much as the title says.

Is there any way to downgrade my CK to a previous, older version?

I recently re-installed Skyrim & the CK on my laptop, & am now experiencing conflicts between the CK and ENB which I never encountered previously, and the preview window has become buggy. It is a blank grey box when ENB is installed, and even when ENB is completely removed it refuses to resize properly.

I did not experience these problems with the previous version of the CK. if possible I need to remove the most recent update & replace it with the previous, more stable version. Is there any way to do this?

Nope. Even if there was, the Creation Kit is only compatible with the corresponding version of Skyrim. The 1.5 CK is not compatible with the 1.4 game, and vica versa.