How to clear Google Drive app defaults?

[cvkone1]

I'm using Huawei Honor Bee running Android 4.4.2 and Emotion Ui 3.0. I've encountered a problem.... As soon as I tap 'Share' on the stock gallery app instead of showing me the list of apps it automatically opens the Google Drive app. I went to Settings > Apps > Google Drive but the 'Clear Defaults' button is not click able ie it is not highlighted. Please help... Any help will be sincerely appreciated. Thank you,
CVKONE1