How to convert 4 array matrix to 3 array matrix?

Hi! I'm currently facing this problem. The image load into matlab has gone through an image editing software and save in .tif format. But matlab can't read and show this image. I've tried using other formats such as .png and it works well. Even though, I still need .tif as my input image format.

I've discovered that when using png

</matlabcentral/answers/uploaded_files/110967/image.png> showing a x b x 3

while using tif

</matlabcentral/answers/uploaded_files/110968/image1.png> showing a x b x 4

Therefore, is there any method or way for me to convert 4 into 3? Appreciate if there is a solution to this problem, thank you.