I recently went through exactly this same situation. I was ready to upgrade to a microswiss all-metal hotend and the catastrophic failure of the print leaving gunk all over my heater block forced the issue. In my case, I opted to replace everything I could including the thermistor and heating element. They are both very inexpensive and you should have a spare laying around anyway in case you need one in a hurry. So...how to clean your heating block...

Fire. Seriously. I used a combination of blowtorch and solvent to remove all the gunk (and mine was a LOT worse than yours...it basically encapsulated one entire end of my heater block, entombing the thermistor, heater and associated wiring).

I used your typical propane torch, holding my heater block in a vise or vise grips. I'd heat it up then quickly wipe away the melted PLA with a clean cloth. Heat, repeat. Then I'd soak the whole thing in some solvent (acetone, MEK, etc). Repeat until clean. Pay careful attention to the tiny setscrew that holds the heater in place...work it free with a hex wrench while it is hot...chances are you got some PLA stuck on there, too. Obviously be super careful when you do this. Ventilation, fire-extinguisher handy, your mom on speed-dial.

When you replace the thermistor and heating element you'll need to do some soldering. This is pretty unavoidable. Those elements come with very long wires attached to them and the Wanhao/MP print heat doesn't need that length. Clip it short, make good solders and use heatshrink over your joints. For the thermistor I simply cut out the center section of the wire and spliced the connector back to the component at the length i needed.

Now, when you put it all back together you will have the option of re-wrapping the heater block with cotton and Kapton tape. People seem split on if this is necessary, but since I'd battled heat creep before I didn't want to introduce any more heat up the block...so I opted to do it. It's a bit tricky if you get the non-punched cotton strips like I did. Luckily I had hole punches handy to make the provision for the hotend and nozzle to get thru the insulation. If you don't have these tools (or don't quite know how to do it), i'd shop around for pre-punched sets.

good luck. Let me know if you need any more help.

here are the parts i used:

https://www.amazon.com/gp/product/B071K8Z9KF/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B01N4KY6TR/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B076NW3GNH/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B01E1HANLS/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1