Well some more information would be handy but no you don't need a deload week after just 2 or 3 weeks of training.
Deloading can save you from getting burnt out mainly from strength training.
Even if training for hypertrophy a form of deload is advisable. A lot of lifters take this into account with how their programs are set out. For example some lifters will increase some form of intensity up to 4 to 6 weeks then may have a back off week where some form of intensity comes down.
This could be intensity of weight lifted, intensity of effort or even just doing less overall volume.
The idea is to freshen up the body and nervous system again and then build back up .
Beginners generally don't need to worry about it too much as they don't recruit enough motor units and the effort used isn't high enough as compared to training to failure Dorain Yates style.
Having said that it is useful to learn how to cycle a program as I discussed above as it will keep you healthier and will avoid you from burning out in the future.
Around the 6 week mark is pretty common for a deload.