The following methods can be used to unclog the hot-end
A clogged hot-end can most of the times be cleaned. There are several methods to do so. The six most common methods are explained below. 

Method 1. Overheated extrusion – No disassembly needed
• Heat up the hot-end to 210 ᴼC for PLA or 230 ᴼC for PET and ABS
• Extrude until the filament starts to flow. For extra effect, pushing the filament through the hot-end while extruding is advised.
• Turn down the temperature to normal printing temperatures. While cooling, keep extruding to check if the extruder still has enough pull. 

Method 2. Tip-drilling - In case of serious clog in the hot-end tip
• Heat up the hot-end to 195 ᴼC
• Drill out the tip by hand with a 0.35mm drill. Don’t use power tools.

Method 3. Dip and pull - In case of an internal clog in the tip.

For this method we assume you are using PLA.

• Set extruder to 230 degC.
• Try to extrude filament, possbily help pushing by hand. Don't do this longer than 2-3 minutes otherwise the top part of the hot-end might become too hot.
• Disable steppers drivers. Go to quick settings menu and scroll down to "disable steppers"
• Set the extruder to 80 degC.
• Pull out the filament by hand. 

This way you pull out filament with the debris which is blocking the nozzle exit. 

Repeat this a few times untill you get optimal extrusion again.

Method 4. Gravity clean - In case of internal clog on top of hot-end.

This happens when you try to extrude too fast at too high temperatures. What happens here is that the pressure in the extruder becomes so high, that the filament starts to creep up the barrel and base, cools down and ultimately jams. Another cause for this kind of jamming can be a defect in the main cooling fan.

• Heat up the nozzle to 220 ᴼC and let it settle for a while. The top part of the hot-end will become hot enough that the filament will sag due to gravity.
• Now slowly push down the filament to check if you are able to extrude. 
• If so keep pushing and set temp to 195 ᴼC, keep extruding slowly until low temp is reached.

Method 5. Inside drill clean - out from inside
• Loosen bolt in front of printer
• Pull out hot-end. Don't dismantle
• Heat hot-end to 150 ᴼC
• Hold hot-end at the cooling fins and insert the long 2 mm drill through the back. Carefully turn so you scrape off any debris from the inside.
• Don’t use power tools

Method 6. (FELIX 3 Only) Inside drill - Last resort, filament got really stuck in top part of the hot-end
• Take out hot-end
• Unscrew top part of hot-end
• Put it in hot-water and push out/drill out the filament using power tools
• Make sure to clean the hot-end of any drilling residue like metal fragments. Use compressed air for ultimate effect.