Why does a charged insulator gets discharged when brought close to a candle? Is it because the flame is oxidising thus providing electrons or some other explanation . only the above explanation came to my mind
 A: There are many possible explanations for this. In general, discharge of a charged insulator happens because either


*

*Excess charge "leaks off", or

*Additional charge is attracted


Now a candle is a plasma - meaning it contains a mixture of positively and negatively charged particles. If you put a charged insulator in contact with a plasma, the "opposite" charge will be attracted until the insulator is neutralized.
But even if the candle is only "close", there are several things that happen:


*

*The insulator is heated: this may encourage thermionic emission. While that is likely a small effect, most insulators don't need a lot of charge to get to a decent voltage

*Particles of soot etc may be emitted by the candle. These particles are typically not exactly neutral - and again, the ones that have opposite charge will be attracted to the insulator

*The candle gives off light: this may lead to photo-induced emission, which would cause a negatively charged insulator to become discharged (and then it would obtain opposite charge).


None of these mechanisms are definitive - but they should give you something to think about. You might enjoy reading [this answer}(https://physics.stackexchange.com/a/130988/26969) to a similar (but distinct) question.
A: This is very common way of discharging apparatus when doing electrostatics demonstrations or experiments.
The flame contains both positive and negative ions as shown in this video.  
So bring a flame close to a charged object has the ions of the opposite charge to the object attracted to the object and discharge it.
