Can you change the 32amp 240v socket to a 16amp socket on your generator?

No!

The 32 amp rating is slightly more than the circuit that supplies it can handle in continuous power supplied, therefore if you replace it with a socket that has a smaller amperage rating (16) you will have the potential to draw through the new socket more (32) amps than it was rated for and thus have a component failure and possible electrocution hazard. The 16 amp socket will physically work but you and anyone who will use the generator in the future MUST ensure that no more than 16 amps are drawn through the socket . I recommend that a like in kind replacement , 32 amps for 32 amps so the full 32 amp supply can be used safely. my opinion.