Dell doesn't have a way into your TPM, or to into Windows its authentication loop. Either would create a gaping security hole very likely to be exploited. So

Dell doesn't have a way into your TPM, or to into Windows its authentication loop. Either would create a gaping security hole very likely to be exploited. So no, Dell can't unlock/decrypt your laptop without your password. The most they could do is bypass your BIOS/EFI password.