I have Nexus 4. On the Call history, tap on the number that you wish to remove, then it will show you call detail for that number. Then tap on 3 dots on the right top and choose "remove from the call log".
I have a Samsung Galaxy s4. I found out how to delete any call, or group of calls from the same number, using my usual method which is to stumble around trying different things until something works.
From the Recent list, tap the number of the listed call. Then tap the Menu light on the lower left of the phone. A set of options will pop up on the lower part of the screen. One of them gives you the option of deleting. Select the delete option, and the call appears with a little box to the right. Tap the box and a check appears. Then, tap Delete at the top right of the screen. A little confirmation screen appears offering the option of deleting or canceling. Tap Delete and the log of that call is removed.
Sometimes, clicking a number at the beginning of this process yields a list of logged calls instead of only one. (I haven't yet figured out why this happens.) You just treat the listed calls as described above with the exception that you also have the Delete All option at the top of the screen.
for deleting a single contact number
1. just tap middle in the contact in your call log
2.you will find call back option and details option
4.now you can see the delete button at right corner
hope its useful - lollipop tips
open your contact, press edit.
You will notice that right below the Cancel/Save header, there are in my case 3 Google...press each of them and delete your number from there.
Hope this helps as well.
(i have a s7)