Ranunculus tubers should be planted in October or November. Contrary to some, the dry tubers do not need to be soaked in water before planting. There should be some bone meal under the tubers but not touching them.
I would leave them in the ground. The survival rate is better than if you remove them.
As long as you don't plant directly on top of a dormant tuber, you can plant summer annuals near them. When the annuals die, cut them down; don't pull them out, which might pull out ranunculus tubers that have become entangled in the annuals' roots.
My garden is planted with perennials, bulbs, shrubs, subshrubs, and ground cover. I have ranunculus in my rose bed along with freesias and narcissus. The bed also contains evergreen daylilies, narcissus, cuphea, primroses, low Camellia sasanqua, and blue fescue. The back of the bed has dwarf Burford holly. One end has a clump of pink Penstemon. The entire bed is covered with pink clover (Persicaria).
The ranunculus, freesias, and narcissus bloom only in the late winter and into the spring, before the roses and daylilies bloom. When they die down and go dormant, the rest of the plants in the bed provide more than enough interest.