You can't free memory. But if you build the black box, you can reconfigure your advanced codes, then save the new layour as an upgraded device, which uses a different bank of memory.
The con: you can only "upgrade" to certain keys, and not to shifted keys, and you can only add advanced codes that are native to that device. For instance, you can't save an advanced code to "1L", and you can't add a code to change TV inputs through the VCR device. Don't read this the wrong way: you can come back after you "upgrade" the new device layout, and then you can add the rest of the advanced codes and shifted keys. My point is, you've still got to be very deliberate in order to maximize memory usage.
As far as deleting keys and macros to make more memory available, that is likely to leave some fragmented memory behind that can't be used. The best way around this is to use the 9-8-0 command to reset the key moves and macros, and begin from scratch. Building the black box eliminates this problem; each time you upload to the remote, the memory is automatically restacked.
