Actually it is not ViaBTC impeding me to withdraw, but Electrum. When I enter the amount, it tells me that it is too small.
Are you saying electrum doesn't allow you to receive the fund you are trying to withdraw to from ViaBTC pool?
If so, that's not possible at all.
Any bitcoin address can receive any amount bigger than the dust limit.
The dust limit for legacy addresses (those that start with 1) is 546 satoshi and for native segwit addresses (those that start with bc1q) is 294 satoshi.
If you can't withdraw from ViaBTC pool, it's ViaBTC that doesn't allow you to withdrawal.