You should only let the child pull it out themselves (or leave it to fall out when it is ready if the child doesn't want to pull it). If you try to pull it out you may cause pain or injury to the child.
Edit to add: letting it fall out by itself is fine - what would be bad about that? The more ready it is, the less pain and bleeding there will be.
Edited to add:
Primary teeth are physiologically stimulated to "shed" by the secondary teeth growing above them. There is little need to interfere with this normal process. This excludes, of course, cavities, infections, delayed eruption of secondary teeth (in which case, the tooth will not be "wobbly"), etc.
Root resorption is a physiologic event for the primary teeth. ...Root resorption seems to be initiated and regulated by the stellate reticulum and the dental follicle of the underlying permanent tooth via the secretion of stimulatory molecules, i.e. cytokines and transcription factors.
Normally, these teeth are programmed, then, to fall out, and failure of this mechanism is not common. There is no need to pull loose teeth; If the tooth hasn't fallen out, it's because there is still some periodontal ligament that needs resorption.
It is highly unlikely that "baby" incisors need to be removed; there isn't usually a problem with spacing/crowding/impaction at the incisor level. This does become more common a problem with canine teeth and molars.
Physiologic root resorption in primary teeth: molecular and histological events
Guideline on Pediatric Oral Surgery