One can reset an Echo Dot even without the help of the Alexa app. For most of the Echo Dot generations, you have to press and hold the specific buttons on the speaker, i.e., usually, the Microphone Off and Volume Down together for approximately 20 seconds until the light ring changes color, which means it has been erased and that it is back in setup mode. With this procedure, all the network settings are removed, and you will have to connect through the Alexa app again after this.