My classmate is having her teeth straightened but she can take her appliance out, can I have my teeth straightened out using a removable appliance?

It all depends on how bad your malocclusion (bad bite) is. Removable braces are those which can be removed for cleaning. They can be used to tip teeth and correct minor irregularities, but they cannot be used to move teeth over significant distances with full control of the tooth's position. Fixed appliances (fixed to the teeth and cannot be removed for cleaning) can be used to move teeth over long distances with the orthodontist exerting full control on their position. Consult your orthodontist's opinion regarding the possibility of using removable appliances, but be warned -their uses are limited compared to fixed appliances.