Ok, well, the short answer to your original question is yes, you can delete logical partitions in an extended partition and then delete the extended partition. Of course you should be aware that all data on the partitions you delete will be irrecoverably lost (or, it would be especially a pain to recover) so obviously don't delete anything you need.
If you then wanted to expand the c: volume into the adjacent empty space you could do that using a tool like gparted:
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gparted.sourceforge.net/ ··· vecd.phpGparted is very reliable but all the same it would be a good idea to back up any irreplaceable data before doing the resize.