How to shrink Recovery HD on macOS Sierra
Reduce the size of the partition containing Recovery HD volume. You can do this by entering the command given below.

diskutil  resizeVolume  disk0s3  660M 

Download and install the third party tool gdisk.
Boot to macOS Recovery over the Internet. Restart your Mac and immediately hold down the option+⌘+R key combination. Release the keys when the spinning globle appears.
Partially disable System Intergity Protection (SIP). From the menu bar, select Utilities➔Terminal. Next, enter the command given below.

csrutil  enable  --without  fs

Boot back to macOS.
Use the interactive command gdisk to change the partition type and attributes for disk3s3. Enter the command given below

sudo  gdisk  /dev/disk0



  Note: The procedure below assumes field 49 (bit #49) is not set. If this field is set, then you should leave the field set.  In other words, if the attribute value is 0002000000000000, then field 49 is set.


Below is an example of using gdisk to repair your Mac. 


  Note: You can exit gdisk at any time without save changes by entering a control+C.


GPT fdisk (gdisk) version 1.0.3

Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): t
Partition number (1-3): 3
Current type is 'Apple HFS/HFS+'
Hex code or GUID (L to show codes, Enter = AF00): AB00
Changed type of partition to 'Recovery HD'

Command (? for help): x

Expert command (? for help): a
Partition number (1-3): 3
Known attributes are:
0: system partition
1: hide from EFI
2: legacy BIOS bootable
60: read-only
62: hidden
63: do not automount

Attribute value is 0000000000000000. Set fields are:
  No fields set

Toggle which attribute field (0-63, 64 or &lt;Enter&gt; to exit): 49
Have enabled the 'Undefined bit #49' attribute.
Attribute value is 0002000000000000. Set fields are:
49 (Undefined bit #49)

Toggle which attribute field (0-63, 64 or &lt;Enter&gt; to exit): 

Expert command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/disk0.
Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Warning: The kernel may continue to use old or deleted partitions.
You should reboot or remove the drive.
The operation has completed successfully.

Enable SIP. Enter the command given below, then restart your Mac.

sudo  csrutil  clear

Recovery the free space back to the Macintosh HD volume. You can do this by entering the command given below

diskutil  resizeVolume  disk0s2  R

Restart your Mac then enter the command below to check the results.

diskutil  list