If you hear your own voice as an echo, the problem is on the other person’s side. If the other person can hear their voice echoing, the problem is on your side.
To fix this, the person responsible should lower the speaker volume. If this doesn’t work, move the microphone as far away as possible from the speakers (If the distance between your microphone and the speakers is 20 cm or less, there will be an echo.)
Using a headset or headphones instead of speakers is an easy way to get rid of the echo.