As per below certification path, Delta exam is only for valid VCP certification. For expired one, you will have to go through VCP 6 foundation exam first and then VCP6 - DCV.
See below options on above link.
+ Path 1: If you hold a valid VCP5-DCV certification
+ Path 4: If you hold an expired VCP5-DCV certification
No, you cannot take the delta exam to get certified in v6. If you hold an expired VCP certification for any solution track, you have to:
1: Attend one of the required training courses.
2: Complete the vSphere 6 Foundations Exam or vSphere 6.5 Foundations Exam
3: Complete the VMware Certified Professional 6 – Data Center Virtualization Exam
See https://mylearn.vmware.com/mgrReg/plan.cfm?plan=64178&ui=www_cert#tab-migration path 3 for more information.
but how come i was able to register for this delta exam at vue? I am paid and registered to take the exam
actually i am registered for the 2V0-621 exam. since i am registered does that mean i can get vcp6 upon pass?
You have an expired VCP5-DCV and want to achieve VCP6-DCV - check path 4 on this page for the requirements you would need to meet: VCP6-DCV Certification
You must take training and pass 2 exams: 2V0-620 and 2V0-621
Pre-requisites are NOT validated as part of you booking an exam, it is your responsibility to make sure you are booking the correct exams to meet any requirements for the certification you are working towards.
If you'd rather achieve VCP6.5-DCV, path 4 on this page shows the requirements for you: VMware Certified Professional 6.5 - Data Center Virtualization
can i skip the training? I dont want to pay $2k for it.
Since your VCP5 expired, you now have to take a required training class.
does it mstter which order i do these in?
can i take the exams first then the class last?
No, the order is not important - meet the requirements in any order and you'll achieve the certification, same as when you got your VCP5-DCV.