Both Uses of

recede
in
Red Queen

But the wall of ice recedes, melting as his gaze softens.†
p. 105.8 *

recedes = moves away or diminishes (becomes less)

But as Osanos advances, the water trailing in a swirling cloak, Cal's flames recede.†
p. 369.6

recede = to move away or diminish (become less)

Definition:

to move away or diminish (become less)

The exact meaning of recede depends upon its context. For example:

"We can't move back in until the floodwaters recede." -- diminish and move away
"Her fear receded." -- diminished
"The waves first advance and then recede." -- move away
"The news story receded into the background as it was replaced by new stories." -- received diminished attention
"a receding hairline" -- diminished hair (each year the line where hair stops growing is higher on the forehead)
"She has a receding chin." -- sloping back (as contrasted to sticking out)