Clearing ::usage message

After having assigned the usage message to f using

ClearAll@f;
f::usage=ToString@RandomInteger@{10^10,10^11};


the mouseover message is stuck at the first assignment while ?f shows the freshest usage message.

How to clear and reassign the usage message so even mouseover is updated?

Env:
Mathematica 12.0 on Win10

• You have use Remove to get rid of usage messages. – m_goldberg Jan 24 '20 at 23:43
• @m_goldberg works! I'll accept if you answer... why doesn't ClearAll work though? – lineage Jan 25 '20 at 3:17

FECacheTemplateAndUsage["f"]
`