There is no way to restart from the beginning. Except by starting a new player.

However, you probably don't need or want to. Aside from buildings, you're going to want everything you have, regardless. RSS, studies completed, Hero levels, and so on. Even any gear you have may be inputs to better gear later. And if not, you can dismantle them. [Keeping your inventory list clean, which can be helpful to K.I.S.S.]

For buildings, you can demolish current ones and raise different ones instead.
[You will end up doing this more than once as you work through what's what. e.g. Barracks are more important than Houses early on, the reverse later as your barracks level up to be able to train more in one go, and houses reduce training time.]

https://support-portal.plarium.com/en/throne-web/faq/buildings/demolition

https://support-portal.plarium.com/en/throne-web/faq/crafting/dismantling-equipment

Note: Before you start, consider the RSS you're farming and troop type you're specializing in. e.g. Quarries add Army Defense bonuses at n31, others other; Foreign expertise studies / Offense has Farms & Houses and Spear & Knight bonuses, Defense & Castle other; different Inquisitor gear brings different RSS & troop type bonuses.

You're not going to get things perfectly optimal, the game is too convoluted to grok a complete heads or tails of it all, but you can make the best informed initial pathway choices you can. It's not wrong to not have all of the above consistent - just go into it eyes wide open.

https://throne.help/en/ can help you try to get a handle on things.