How to remove / reduce wrinkle after adding subdivision surface modifier? [duplicate]

Question

I'm a beginner at blender . I added subdivision surface modifier to my object and chosen the Catmull-Clark . In my tutorial there is no wrinkle on the object , but for a reason i don't know there is a wrinkle on my object. The wrinkle does not appear on other part of the object , only on one specific area .

How do i remove the wrinkle ?

Before and after adding subdivision surface modifier :

With shading set to smooth , the wrinkle still visible :

Edit : here is my blend file (uploaded at https://blend-exchange.com/)

Answer 1

Your original structure:

Now, you can add one loop cut and one inset in the following manner:

Then increase the subsurf resolution to 5 or 6, then you get this:

If you still want the original bends in the stick-structure, you can add 2 loop cuts for each bend like this:

Answer 2

I have modified your mesh by adding edge loops and removed the wrinkles.

Here is the file https://blend-exchange.com/b/OZnLl2AZ

To remove your wrinkles and also curving the top of your mesh

STEP 1

You can start of by insetting the top face by selecting your face and pressing I on your keypad. So that you have something like this.

STEP 2

Now select the edge loop closest to the top face and press G twice on your keypad to edge slide and bring the edge loop down so that it makes the top curved and circular like you asked for.

STEP 3

Now inset the top face again

and then edge slide the loop again by pressing G twice on your keypad.

STEP 4

The last step is to tab into object mode select your apple stem and then Right-Click shade smooth Also I strongly recommend that you should make a few tweaks and adjustments to your mesh by just going around and selecting edge loops and rotating* and scaling them.