Keep refining/miniaturizing the technology. from mainframes, PCs, tablets, mobile watches to tiny chip in brain. In energy from coal, oil, electric, solar to ze

Keep refining/miniaturizing the technology. from mainframes, PCs, tablets, mobile watches to tiny chip in brain. In energy from coal, oil, electric, solar to zero-power. Eventually the grossness will disappear to a great extent. leaving little to know artifacts. The remaining artifacts including the dwelling structures get recycled into their raw sources given sufficient time; especially if remain under water for good amount of time. Continents may fall into ocean destroying the evidence more quickly. This is only when you are expecting a civilization as current one. How about those who weren't dependent on technology ever - they may have chosen a route to discover about the nature, the universe and themselves drastically different from that of ours and hence we, enamored by a false sense of superiority, fail to even contemplate of such possibility let alone any chance of discovering an evidence of their existence.