How to remove ancilla bits from results?

You can (and you should) always uncomputer ancilla qubits. This can be done by application of inverse gates in inverse order to original ones which prepared states of ancilla qubits.

Here is an example:

The purpose of the circuit is to calculate $q_0 ,text{AND}, q_1 ,text{AND} q_2$. To do so, firstly $q_0 ,text{AND}, q_1$ is calculated and result is stored to ancilla $q_3$. After that final result is obtained by $q_2 ,text{AND}, q_3$ and stored to $q_4$. Finnaly, inverse operation (note that inverse gate to Toffoli is again Toffoli) is applied. As a result, state of ancilla $q_3$ is returned back to $|0rangle$. This value is returned during measurement. If you do not want to include ancilla to measurement, simply do not put the measurement on qubit $q_3$.