This question is subject, like all others, to capricious changes to Libra Terms, Conditions and Implementation. Facebook values its bottom line and is taking that, and only that, into consideration determening actions to protect your privacy, the security of your wallet, the fiat it is based on, the value of its coin and which Trusted Partners™ to allow to control Libra.

Right now, it is not reversible or changeable. There is a system of rent, so it isn't permanent(although evicted data can be reconstituted via crypto-proof).